Please help me and my daughter. She has had an incurable spell of head lice for nearly 4months now.?

I am very highly educated in this area and have worked in public school systems, private daycares and nursing homes. I know all the products by heart and all the must haves and must do's concerning getting rid of headlice with no results!! It never fails, after about 2weeks it comes back and sometimes even worse than ever. We have sprayed her locker at school, checked her friends's heads before they all play ( very embaring) , treated the family, treated the pets and sprayed every fabric and washed every washable. Even the car and coats and all. Do any of you out there have any home remedies or specific things to help my little girl. She could seriously test positive for the treatment RID in her blood we have treated so much. We have even used the enviromental non chemical treatments. Please help.