I have found an effective strategy when the conversation goes quiet is to stare off into space and look slightly bored. This puts social pressure on someone to re-start the conversation and because girls are usually more attuned to reading this social pressure they will, 9 times out of 10, crack before you and start up the conversation again.
Of course this relies on them actually being interested in you, if they don't spark the conversation back up then it probably wasn't going anywhere anyway, no loss. And of course it wont work if you are running into pauses in conversation every 30 seconds, this will just get tedious for her. If you are running out of things to say this often then I would suggest you just talk to everyone, as much as possible, and develop some common conversation topics you can relate to.
It is a highly effective tool however because she quickly realises that she re-started the conversation, so it puts her in the position of chasing. She will remember chasing you long after the interaction is over and that is a very powerful thing as far as attraction goes.
I think there may be some articles on this, I respectfully suggest you look them up if you are interested in knowing more.