We already talked to the principals, the teachers, and the superintendent. The next step would be to talk to the board of education. From what you and LoveBug said, it seems to be very hard to make a case, we pretty much decided to send her to a private K.
We convinced our daughter that we just want her to have more fun. It seems to be working. She will make new friends pretty soon. This is much harder than sending her to 1st grade. It was a tough decision to us, too. Thanks again for your adivce.