This is an interesting question. I am not entirely certain that there is this level of idealism in Eliezer at any point in the narrative. Even before he is sent to the camps by the Nazis, Eliezer did not possess a capacity of envisioning a world better than what was in front of him. This is not to say that he demonstrated a love of being. While he was concerned with his religious studies, there is little in the text to indicate that he saw this as a transformative element over the world that existed. Rather, he is able to see the challenges in religious study such as asking God the questions as opposed to seeking to generate answers from the divine. Here, one does not see a dream or vision of a better world, but rather a study of what underscores this one.
Certainly, Eliezer does not do much in terms of envisioning a new world in the camps. He does not dream of a better world. He struggles to survive in the world that is in front of him. The anger and sense of resentment he feels at being betrayed by the divine is what prevents him of dreaming of a better world. Eliezer's anger at God and at the situation in which he lives are realities that he battles throughout the narrative. In this, Elizer's desire to survive at the most basic of levels prevents him from actualizing a better world. These dreams were not a part of the experience revealed in the narrative. At the end, when he sees himself in the mirror for the first time, he does not see a better world. He does not see a transformative vision where justice and righteousness are restored. He does not see hope and a world of what can be. Instead, he sees a corpse. He sees what is. He sees the reality in front of him. It is here where I think it becomes evident that Eliezer does not dream of a better world in Night.