Dynamic, Paul Vincents, Ken Hodge's ( New outfit). All are cut from the same cloth and will give your kid the individualized attention and correct flaws. Expensive but far less than private lessons. Make sure your kid continues skating and working on what he learns in his spare time.
We've done these, and I'm a fan. They will help your kid to improve. These are not the same as private lessons.
Around 13-14 years old my son did a small group (3 kids) skating session for 2 hours a week for 6 weeks. Was the best money we ever spent in hockey. Made a huge difference.
Find 1 or 3 teammates or friends with an equal drive to get better and defray the cost of the private lesson. Choose carefully (coach/instructor as well as other kids), and if you do it right your kid will benefit greatly from a regular program over the spring/summer months.