I'm a bit baffled that you are missing the thematic current here across these scenes.
John Blake: "I don't know why you took the fall for Dent's murder, but I'm still a believer in the Batman. Even if you're not."
Bruce no longer believes in the Batman. Because the Batman failed to save Gotham's soul.
Bruce Wayne: The Batman wasn't needed anymore. We won.
Commissioner Gordon: Based on a lie. And now this evil rising from where we tried to bury it. The Batman has to come back.
Bruce Wayne: What if he doesn't exist anymore?
Again, Bruce no longer believes in the Batman. He's trying to convince himself that its because Batman is no longer needed, but Gordon shoots that theory out from under him, so Bruce is left with nothing but his lost hope: "What if he doesn't exist anymore?" Gordon and Blake both believe in the Batman, Bruce doesn't. But their belief spurs him to action.
Then, right after this:
Miranda: You have to invest to restore balance to the world. Take our clean-energy project.
The language of restoring balance is an intentional callback to Ra's similar line in Begins. The scriptwriters are making an intentional parallel between the crusade for justice and the clean-energy project. You may not think that Miranda as a character is making that intentional parallel, but the movie certainly is thematically.
Bruce Wayne: Sometimes the investment doesn't pay off. I'm Sorry.
Miranda: You have a practiced apathy, Mr. Wayne. But a man who doesn't care about the world doesn't spend half his fortune on a plan to save it. And isn't so wounded when it fails that he goes into hiding. Have a good evening, Mr. Wayne.
Bruce is trying to be apathetic about his identity as Batman. "We won." Practiced apathy. But he knows deep down that they didn't win. Deep down he's wounded by the failure to save Gotham's soul. Its not enough to restore order when there's no redemption. This is why Catwoman's character is so important to Bruce's arc... she gives him someone to redeem, which also spurs him back into action.
You've got to keep in mind with this dialogue that Miranda wants Bruce to take up the mantle of the bat again. Its perfect for her plan of revenge to have Bane obliterate Bruce Wayne AS Batman, not just some cripple Wayne but Wayne in the garb of his crusade. Its about breaking the symbol just as much as about breaking the man.
Bruce Wayne: I retired.
Fox: Well, let me show you some stuff, anyway. Just for old times sake.
Again, Bruce no longer "believes" in the Batman, but Lucius Fox does. Another nudge back into action.
Bruce Wayne: If this man is everything that you say he is, then this city needs me.
Alfred: The city needs Bruce Wayne. Your resources, your knowledge. It doesn't need your body, or your life. That time has passed.
Bruce Wayne: You're afraid that if I go back out there, I'll fail.
Alfred: No. I'm afraid that you want to.
Again, Bruce is taking up the mantle, but he hasn't taken back Batman's mission to redeem Gotham. He's going out to address a threat. Alfred believes Bruce can do more good as Bruce Wayne. He can address the problems in Gotham's soul. But Bruce doesn't believe that is possible, just like he still doesn't believe in the energy project. All he believes is possible is addressing the symptoms, not the disease.
Its through Blake that Bruce reclaims the notion of Batman "as a symbol." At last Bruce regains his belief in the Batman fully when "the dark knight rises" out of the pit. He paints the fiery symbol on the bridge as a sign of hope for Gotham. That's where this arc leads. That's the whole point. Its not just a physical story, its a spiritual one.