ummm Let me be competely honest with you from someone whos been down that road a few times, on the female perspective.
After so long of being a guys friend, thats how they stay inless something changes. That usually doesnt happen inless you stray away from her for awhile or you help her out in a drastic situation, etc. you get what I'm saying? You will never be anything more than a friend inless something changers her mind.
Secondly, shes keeping you as a last resort, I think, by stringing you along by saying how shes into you yet doesnt act on it. The hurtful truth, women like to keep back ups for when all else fails. We want to know we are adored even though we have no intention of acting on it, sorry guys. This little 'pet' phase lasts all through jr high and some of high school. I'm not sure how old you are, but I'm guessing the area where your still figuring out who you are and she is really lost on how to do this.
My best advice, is break free of her - for awhile. Dont sever the friendship you have going but take a step back. You need to show her your not her pet and if shes not going to be serious then you want to stay friends while you look for something real. Dont hang out as much, dont seem as interested as much, but still be their for her if she needs you.
Sadly, I'm telling you to act not interested, as much, and it will bring her back to wanting you. Nothing like having to recaputre prey - let me tell you.
^_^
and before all the female create a lynching party, I'm not saying all women are like this, but we all have our own phase of it in same form or another.