My last dirt bike I removed the chain and cleaned it in solvent after every
day of long riding. I would skip the days that I went on just a short run or
two. Remove the chain, clean it in solvent, blow it out good with compressed
air. Then I would soak the chain over night in 80-90 weight gear lube, then
hang it up so the excess would run off.

It was allot of messing around, but I could get many years on a chain!

If you could get your kid to do it once a month, or/and everytime he road in
wet conditions, I bet you will get good chain life.
Greg