Listen to her spiel and Joey's comments. (If you listen to the commentary track here, you'll discover that this is almost word-for-word the spiel Dave Gilbert got when he visited a real street "psychic." Makes me shudder.)
After you find Jeremy's phone --
How do I find Jeremy's cell phone?
-- confront her with that and say everything Rosa has to say. Not surprisingly, Lisa gets flustered, then angry, then throws you out.
How do I get Lisa to tell me more?