Girl acts like she likes you but says she doesn't?

So there is this girl I like and I told her that I liked her at one point and asked her if she liked me. She said that she wasn't into me. That was about 9 months ago. She act as if she like me. We will text each other every second day for hours on end. We hang out, she invites me to her friend's parties and even asks me to go to movies with her. She regularly calls me darling and sweetheart every now and again. When she's been drinking she gets real friendly and loves to stand close, like pressed up against me and noses almost touching if were talking. Just last night when at a club she was dancing with her friends and I was sitting down a little bit away, when she seen me she came and sat with me and kept talking for at least 45 mins until her friends came along and pretty much had to drag her away from me. So I was just wondering why would she act like this if she doesn't like me? Maybe this is just her playing hard to get? But since she knows I like her you think if she liked me she would just say it? Have any of you girls done anything like this? What should I do?