How to make my friend realize she's not AP material?

I applaud your desire to help your friend but it is not your job to get her into an Advanced Placement cl. Continue to be supportive of her but remember a true friend always tells the truth and if you really count yourself to be her friend you will be honest with her and tell her the truth. Therefore, let the teacher, the Advanced Placement Coordinator, Counselor, etc. tell her the news, not you ... if might cost you you a friend or at least an acquaintance.