After rescuing Mr. Freeze, Batman, Freeze, and Oracle agree that they need Ra's al Ghul's blood to cure the Titan virus. It seems from this conversation that Batman and Oracle know about the Lazarus Pit already.
When meeting Talia in Wonder City, Batman says,
"Where's Ra's? If he's dead again, I need you to wake him up."
After fighting Ra's, Batman talks to him, saying,
"The Lazarus Pit has corrupted your mind. Think about it. If your Pit falls into the wrong hands, you'll be powerless to stop centuries of destruction."
All of this implies that Batman knows all about the Lazarus Pit already.
But then, when Batman talks to Oracle, he says,
"Ra's and his forces are [...] extracting some kind of naturally occuring chemical he's called 'Lazarus'. [...] When I'm done here, I'll need to investigate this Lazarus technology further."
This implies that Batman is only now learning about the Lazarus Pit.
Is there anything I'm missing here?