Keep bugging the school. If they're dragging their heels find someone at the School Board office that can get her evaluated so you know what she needs help in. If she can't learn it, all the rewards in the world won't help. It sounds like you've tried your best, so speak up and get help. I'd talk with her teacher, counselor, whatever before you make a decision about holding her back. It might be best for her in the long run if you can't get any other help. Best of luck.
she will be 9 years old in May, So I guess she is kinda the youngest. Never thought of it that way because she as tall if not taller than most of the kids
When is her birthday? Is she one of the youngest in the class? This is a big point concerning retention; it does work best if the child is younger than most classmates.