Just let her be and support as best you can by lowering high parental expectations, hiring a tutor, asking guidance counselors and teachers for help, suggesting joining extracurricular clubs, inviting her friends over and may be letting her see a therapist who can help her cope with adjustment issues. You may not see desired effects in changing homes, switching school system and starting from square one yet once again.
My sister was never a good student and struggled with some learning disabilities. When she graduated she was turned down by our flagship state university. She did a junior college for two years and then enrolled in the flagship school. I truly believe that you don’t always have to enter college ‘through the front door’. My daughter is a very motivated student and hence very stressed. I am always reassuring her that she will get into college and we will figure out a way.