Don't know if this is helpful, but we used Risperdal on an as needed (PRN) basis. They even make a melt on your tongue version. You could wean him off (what dose is he on?) and then get a prescription for using it as needed if there are only certain days that he seems to need it.
If you are really not sure he needs then then it might be good to wean him off of it. You can always put him back on. Just maybe wait until after the holidays to make a definitive judgement about whether or not it had a positive effect.