Just a thought, without knowing your app very well or the usage the kids make of it, but it sounds like some kind of new feature unlocked via an IAP may make se

Just a thought, without knowing your app very well or the usage the kids make of it, but it sounds like some kind of new feature unlocked via an IAP may make sense. Right now it looks like you're releasing each content pack as a new app, that's also free. There's your problem. Release content packs as IAP, give 3 away for free and charge $1 each for new content packs. There's your revenue stream. If the app is really teaching the kid stuff, parents will probably pony up and pay a few bucks now and then, since they care about their children's education.