Return the service to the Dvir of your house, also the burnt offerings of Israel (Shemoneh Esrei. Blessing of Retzei)
The Dvir is the term used in Melachim 1 (6:19) for the Kodesh hakodashim (Holy of Holies) which houses the Aron (Ark of the Covenant).
This raises a few questions. Why is the kodesh hakodashim called Dvir? Why are we requesting that the service return to the Dvir, when most of the service is performed outside on the Mizbeach (altar)? Which service are we asking to restore?
The Rambam describes two types of service in the Moreh Hanevuchim 3:32. The truest sense of service is internal, when a person is actively thinking about the knowledge of God. But the majority of our service is in action. The purpose of this second service is to accustom us to His service by removing false ideas. In this chapter the Rambam explains at length the purpose of animal sacrifice as an antidote to Idolatry. The system of sacrifice transforms the kind of service which was socially self-evident; limits it to the degree possible and redirects it towards God . Even though the first service is higher by nature; as long as our energy and interest is in the physical world our primary involvement must be with the second. Through this second type we learn to recognize and apply wisdom in our lives and slowly escape from a life governed by fantasy. (Prayer is also a member of the second class, but serves an intermediate role. It is external speech, but since speech is a direct expression of thought, it guides us towards a life of thought. This is why “any prayer without directed intent is not a prayer (Laws of Prayer 4:15).) As our apprehension of the reality of mind becomes greater more of our focus can shift towards knowledge but we never fully escape the need for a connection to the physical world.
Dvir comes from the root Davar, speech. The Kodesh hakodashim was the source of God’s speech to Moses from between the Keruvim. The theme of the room is God communicating to man. Inside the Aron are the Luchot which record God’s speech to us at Mount Sinai when he gave us the Torah. On top of the Aron are the Keruvim, which reflect the idea of angels; to teach us the reality of mind separate from matter which is the source of prophecy. This is why it is called Dvir, it is the room of God’s speech. It is the place where the highest service takes place, the service of knowledge of God. Even on Yom Kippur, the one time a year when regular service occurs inside, the service emphasizes the idea that God is known only through an obscuring cloud, and that our materiality is the source of that veil.
The Temple therefore has two foci. One is the Kodesh Hadodashim, which points to the ultimate service which is our aspiration. The second is the Mizbeach, the place of animal sacrifice, which addresses our current level and psychological needs.
David emphasized this duality: “”This is the house of God, and this is the altar of sacrifice for Israel” (Divrei hayamim 1 22:1). In its essence it is the house dedicated for God, but for Israel it is the altar of sacrifice. Since Israel is a nation service must be defined in a way which is accessible to all people and not only to rare individuals. This is the uniqueness of Torah; it is a law accessible to all, which guides all people, not just philosophers, towards living a life of knowing God and serving Him in a life of action which both applies and leads to that knowledge. Thus in an educational framework the actions, such as the sacrificial order, take priority; while, in its nature, service in knowledge is primary and is the objective and cause of the order of the service in action .
This duality is expressed in Halacha as well. In chapter 1 of the laws of Beit Habechira the Rambam discusses the Beit hamikdash as a whole, in this framework the Kodesh hakodashim is, as its name implies, the essence. But in chapter 2 the Rambam shifts focus to the mizbeach, and its unique history and identity.
Prayer also includes both of these ideas. On the one hand we face the mikdash during prayer, a direction ultimately pointing to the kodesh hakedoshim, which is the physical stand-in for the direction of the shechina (Laws of Prayer 5:3). On the other hand the times of Tefilla are based on the daily sacrificial order (Laws of Prayer 1:5-6).
In Retzei, the blessing requesting that God find favor with the Jewish people and their prayers, we request the return of service to the mikdash, the place of shechina, in these two frameworks. First the service of knowledge in the Dvir; and second the service in the burnt offerings of Israel, necessary for achieving the first. 
In the same chapter the Rambam explains that the idea the objective of many Mitzvoth is removing falsehood, not necessarily producing something positive, is an important example of God’s merciful action in the world; the study of which serves as the basis of the Mitzvah to imitate his ways.
 This is related to the halacha from Yesodei Hatorah 4:13, quoted in the previous post, which prioritizes the study of the Davar Katan of halacha over the study of the Davar Gadol of science and philosophy in one’s sequence of study.
 In reality even the higher form of service is expressed in action of following God’s ways, since our knowledge of God is of His actions not His essence. But this sense of action, embodied, for example, in the life of Avraham is action of a different kind directly based on his abstract knowledge of God.
 This request for God desiring our prayers is very different than that of Shomeah Tefillah which discusses prayer as request