I found some good advice in the Baseball Drills and Coaching Tips blog recently. Check it out --http://tinyurl.com/ygs9sv8.
The drill introduced here is pretty typical, but the advice behind it is helpful. The thought is that you need to regularly introduce new drills to your team to help keep their interest. Run through it a few times late in a practice, then watch the players work to get it right when you execute it at the next practice.
I've seen children respond very positively to new drills. Some drills don't work well and that's okay as long as you realize it and move on. But when you find something that works, try it again! And the only way to find out what will work is to continue to introduce new drills from time to time and keep things "fresh".