Keep in mind that many families return to the same exact camp grounds/cabin/house on the lake summer after summer and it never gets boring. It is actually the comfort of knowing exactly what to expect. The way you can picture it in your mind before you go. Talking about where you are going to eat, and remembering past trips...
Your family trip to Disney will always be special and it will always be changing because the children's interests are changing.
I would begin by talking about which rides/attractions they are going to try this year. Maybe something was too frightening before and now they are ready to tackle it.
Have you done the mouse boats yet? Your children are too young to drive on their own, but you can go together. Any of the lake front resorts will rent them. We like Wilderness Lodge. They are next to a small, quiet, sandy area.
I'm sure you've done Beaches and Cream, but boy do I love that place. Worth the wait.
Go to the Steve Soars site and each pick something different you've never seen before. Have you met Push at MK. (He's a cutie and lots of interactive fun.) Which entertainers have you yet to see at Epcot?
Have you visited other resorts? Maybe a carriage ride? Or fishing at POR?
Check out the allears.net for all the neat little things you can do at the different resorts. I would like to go to the AKL, watch the animals, and have a drink at the bar.