The overwhelmingly biggest reason kids play cricket is to have fun. This is especially true at younger age groups. However, even at the most serious level if a child is not enjoying their game they are more likely to drop out and do something else. They may be lost to cricket or even to sport.
For this reason every good coach ensures that fun is the second priority after safety. That means doing more than endless skill improvement drills and mindless nets. You could do something as simple as add a competitive element to drill or go as far as letting free play reign for the last part of your sessions.