Talk about you're favorite things to do, but also ask about hers. Girls love to talk about themselves if you seem interested in what they're saying, well at least I do! (: I have fun playing the 20 questions game in the beginning of an almost relationship, it's sort of like an ice-breaker! Have fun and good luck!
Talk about likes and dislikes... I'm sure you will find things in common or even differences which will help your convo flow ??
make it a bit deeper convo than the first date. Remember women love to talk about themselves, so let her talk and most important, listen to her. Talk about your families, interests, maybe some memories as kids, dreams for the future, etc.
You should be using material obtained on your first date as conversation material. You must find common interests to talk about as a base and then exchange opinions and random ideas in an attempt to fish for more common ground. If worse comes to worst, comment on something in the vicinity.