You may want to talk with the school counselor. He or she may be able to give your daughter some individual time or include her in a small group on friendship. The counselor or teacher could also lead some friendship activities with the class and encourage new friends on the playground and at lunch.
You can also help your daughter find new friends. Let her invite one or two friends from school or from the neighborhood over to play. Encourage your daughter to get involved in groups to make new friends. Joining a Girl Scout troop, a soccer team, or a church group can allow her to make friends away from the issues at school.