I lack the knowledge

In the area of motivation, for one individual in particular. I think I'm just going to have to take the reins back from her and make her roam around. Whenever she messes up she refuses to admit it, and cannot admit her wrong or that she was taught differently. Therefore I am coming closer and closer to regretting my decision to advise on her advancement. She is still in the comfort zone of not really being the one in charge and therein not taking responsibility. Of the list of things that she needed to move up, she has done 0 with all of her time off, and still not done what was on her list of things to accomplish. With this seriously lack of motivation, I don't know how to inspire her other than take away all of her privileges. I hate to do it because I see where she could go, but right now she isn't ready. I only hope that by the fall she has grown up enough as a person to ask for help when needed and own up to her, yes her, shortcomings without blaming another. Then move on and attempt self betterment instead of saying oh it's okay if I'm that way, you should change instead..