Perhaps, it is time you wore your serious face and talked to her about it. Don't tell her that you don't like her because it will hurt her feelings. Just tell her that you think she is nice and all that, but you just aren't ready to get involved with anyone and would appreciate if she doesn't mention anything about it again.
Well, dont seem interested. Just, when she talks to you, dont care. You know, like super short answers, never look at her, always be kinda serious. I dont think she will still be after you if you dont pay attention to her.