Oh that's tough. Trick not really she'll either like you or not. I asume you have been yourself when talking to her right. Not putting on an act to get laid like a lot of guys do.(that is bad if you really like her). Being yourself talking about stuff you like you could try asking her to something social but not a date thing just chilling but you can't do that to often other wise you become the friend. If she's attracted to you the more time your around her the more it will show its trying to figure out if she like likes you or just likes you as a friend.
Don't buy/offer her a drink!!! That makes you like every other guy. Which you do not want to be.
Be sure of yourself but that does not mean being overly cocky either.
I obviously know nothing about her but girls love to talk in general let her and actually pay attention. We can tell when your not.