Anything don't overthink it and act like yourself... just make sure you really want something with this girl. I met a guy after 2 weeks of on and off talking and he ended up just wanting sex after promising all these future plans like prom, road trips and places that he was gonna take me to eat so if just be real with her. Good Luck!
Act normal and be yourself. You can talk about a lot of things. Talk about how happy you are to see her and then go into small chit chat stuff. Like simple things like life, her dailey routine and family, etc.