You're talking to a hottie at the bar and chatting. You're talking and talking, having a good time, when suddenly the conversations comes to a standstill. What do you do?

What I'm asking for is any move, comment, question, strategy, what have you. Do you consider it a sign of non-attraction, and move on? Do you have a one-liner that you drop? Do you ask her to dance? (If there's music?)

Is there a be-all-and-end-all strategy that hands-down works without fail? Help a brother out! Thanks!