If the end-goal is realistic and aimed toward playing in college then you move on to F.S.; if the kid get playing time (again, usually as a forward) as a freshmen / sophomore then two years high school and then off to prep for a repeat year or then off to a real f.s. team. Staying in high school hockey does less than zero for the kid's game and there are tons of examples of the 'all-region' 14 year old players flaming-out before their senior year of h.s. hockey. Bad hockey, bad habits, bad coaching only pushes the kid's game one direction and that is down.
if the kid is clearly one of the better players or dominant in HS his first 2 years, move on to a prep or JR team if that's what the kid wants to do.
However, the kid better be a very good/dominant player to even have a chance of playing in college. If not, that's ok as well. Stay in HS, enjoy it, have fun.
If you try to force it and make it happen and the kids really not that good, you're just going to spend a lot of money chasing your tail.