Hi Stefanie! We first took our son to "'Meet Mickey" when he was around your daughters age, and I cannot tell you how much we all needed little breaks to let him run out some energy.
In Disney's Animal Kingdom you'll for sure want to check out
The Boneyard. One side is a playground with tunnels, slides, and a massive climbing structure. (The inclines are all ramps and staircases, so you can escort her with ease if she needs a little help.) The other is a giant sandbox where kids of all ages can dig to uncover a prehistoric fossil.
At Disney's Hollywood Studios check out the
Disney Junior Live on Stage! show. This indoor silly live-action show is full of dancing, songs, and your favorite Disney Junior pals. (Also bubbles!)
In Epcot I would encourage you to find one of the many live bands around the World Showcase and let your little dance her heart out while you and your husband enjoy a treat from one of the many culturally accurate drink and snack booths, or quick service restaurants.
And I have two favorites in Magic Kingdom Park. First would be the Circus-themed indoor play area inside the queue of Dumbo the Flying Elephant. Here you're given a restaurant-style pager to hold your spot in line to allow your child a chance to run off some steam. There's a dedicated toddler section, and best of all is when it's time to go it's also time to ride! The other in Magic Kingdom is a tiny tot play area across from the entrance of Splash Mountain.
There is always swimming at your resort hotels pool, the majority of which are heated year-round, and each hotel also has a playground. Your whole family is going to remember this trip forever!
~ Kristen