Hi My Name Is Balinda And I Have A Son

hi my name is Balinda and I have a son that has moderate autistic spectrum disorder (non-verbal) and he has been taking Guanfacine for irritability due to his autism. but I think he developed a tolerance to the medication because he is returning to the aggressive behavior he had before being medicated. what do you suggest I do? his neurologist is 1 1/2 hours away and his insurance won't cover increasing the strength of the meds.