medical nessecity

i am new to massage and dealing with insurance companies. So that being said if anyone can help. I have a lady that is a runner. Was having back problems and was working on her, after 6 visits she is back to normal daily activities and running. I would like to continue seeing her on a monthy bases to keep her from returning to her original body state. In order to get more referals i have to show a medical nessecity or its a no go and she will have to pay out of pocket. Is it possible to show medical nessecity .  I can show how to prevent it from returning but that isn't covered. Thanks if anyone can help me or direct me in the right area.