ikno, you sound like a talented and dedicated teacher! We are lucky to have you in chinuch!
R. Brezak has a great story of a Rebbe who told a child, “I don’t care how much trouble you make, I will love you anyway.”
A similar story is with a rebbe who went to visit a child’s house at night and told him, I heard that you have a great stamp collection. Can I see it?
Point I’m trying to make: Can you give her some special attention? Can you find something that she’s good at and give it as a class project, with parents/principals/other classes coming to see it?
Good luck, and once again we’re lucky to have such talented and dedicated teachers teaching our daughters and sisters!