According to Neeson, who neither confirmed nor denied that he's in the new film, he has no idea what happens in it, or what the future of Ra's (and Talia) al Ghul might be. “I was on set for maybe an hour and a half and the director didn’t tell me anything of what it’s about," Neeson told the rumor site. “So, I’m being very honest when I say I have no idea what’s going to happen.”
As Bleeding Cool points out, it's difficult to imagine that Neeson (assuming he's telling the truth) could have done very much in an hour and a half, and it's distinctly possible he was just visiting. Still, clips from the trailers have shown a scene that appears to be a flashback to Batman's training, leaving open the possibility that Ra's will appear either in that, or in that other rumored flashback scene.