Just start a casual conversation like you usually would. There's no one magic word or phrase you can say unconditionally that'll work every time you start talking to someone, so find whatever you think works best and go from there. Also, don't expect anything, be aware that the conversation could change at a moment's notice and go in almost any direction. If you're the kind of person that likes puns or she does, I'd suggest you make a little something out of how you two lived so far away for so long. And most of all, enjoy yourself!