I would plan to hit the parks intermittently. Early in the morning, break for your resort & the pool (and the kids can relax and recharge-you'll probably need it too), then go back in the evening.
Plan a water park day!
Not sure where you're from, OP, and I know you said "besides the heat", but really, some people aren't prepared for the intense heat. Florida sunshine is not a force to be reckoned with. Constantly reapply sunscreen, and get in the shade when you can. Florida is (typically) so hot in July, tourists also need to be mindful of heat exhaustion and heat rash. The old saying is it's hottest from 10-2, but here in Florida, it feels like 12-4 to me. Maybe try to plan an ADR for lunch at whichever park you'll be at to get energy and cool down.
Invest ahead of time in one of those water mist fans and take that to the park. Also, lots of cold bottled water.
This all sounds so ridiculous when I read over it, but I'm continually amazed by the amount of tourists who come here, roast themselves and their kids, and end up collapsing from the heat.
Sounds like July is the better plan for your family, so keep reading up on surviving Disney in July and you should still have a great trip.