I read something somewhere along the lines of, 'Charm is great for the first 5 minutes. After that, you better know something.'
Sounds like you have the charm, but the conversation just fails once that initial approach is completed. Sounds like it's time to transition and move into something a little deeper.
I like to do a 'psychic' transition. I'll ask her to give me her hand (free kino), and I'll tell her things about herself (Forer Effect
http://skepdic.com/forer.html). That alone should give you plenty to talk about, and involves more personal matters.
CHAT