Here's a way to get families remembering all the fun times their kid had at camp and thinking about you in the off-season.
When a camper makes an arts & crafts project, store the project at camp. Don't let the child take it home.
Several months later, say in November or December, send the craft to the family with a handwritten note saying you were doing some site maintenance and came across this beautiful project their kid made at camp and you thought they might like to have it.
They'll be floored!
Not only will they LOVE the fact you even found it in the first place, they'll be grateful you took the time to send it. They'll probably hang it on their wall or something. They'll definitely call you to say thanks, and you know they'll share this story with their friends!
Trust me, this one works. I'd rather do something like this than send the family a calendar or something they'll probably throw in the trash. I've used this tactic forever at Aloha Beach Camp and I've never been disappointed with the results. Give it a try yourself!