I am working a miser's dream children variation into my routine. I picked up the idea from Sammy Smith's book "Big Laughs for Little People", except I am developing my own style and patter. Maybe you can add that in? Its not too long and both the children and adults will enjoy it.
Perhaps a silk or hanky routine may add a little to your show. Another idea is incorporating a puppet act. It does not have to be a vent performance as a hand puppet with a solid routine can work just as well. I think it is a good idea to break up the magic.
I hope this helps!