BeitarYid
I certainly hope you asked a Rav before doing what you did and I must say that your ignoring him is not yashrus and is not a good idea and will teach him avoidance which is a horrible middah and can hurt him greatly in future relationships. If you think its a good idea for him not to have it treat him like an adult not a child. In my opinion (based on experience with similar situations in America) your approach is yatza scharo behefesido.
“My son is pretty cool with it and has actually had a very good year. Occasionally he asks for it back and i change the subject.”
evidently he is not “cool with it” otherwise he would not be asking for it back. if teenagers feel that they do not have what to work with they will invariably rebel at some point.
One last point is that just because something seems to be effective does not make it a good idea or good chinuch. I am sure corporal punishment might work on a minority of 15 year olds. It is still assur to do so.