Hi, Wendy!
Even when my kids were 3, we always found plenty to occupy their time in
Epcot.
First, a meal at
Akershus Royal Banquet Hall will delight your little princess, and you can pair that with additional Princess and character greetings all around World Showcase. You can find Aladdin & Jasmine in Morocco, Alice in Wonderland, Princess Aurora, Belle, Mary Poppins, Mulan and Snow White as you tour the World, which also gives you another option for Princess sightings should you choose not to dine at Akershus.
There are lots of
attractions and activities for little ones at Epcot as well! In addition to
Kidcot Fun Stops, you can visit Future World, where there are many indoor interactive entertainment areas geared for Guests of all ages. My kids' favorites included Advanced Training Lab, Innoventions, The Seas with Nemo & Friends and Turtle Talk with Crush, to name a few.
If you'd like a chance to dine with some royals and other characters, but can't spare a park day and don't have access to a Park Hopper, then consider dining at
1900 Park Fare at Disney's Grand Floridian Resort & Spa. This might be a great option for you step away from another park, such as Animal Kingdom, for an evening opportunity to light up your little princess's night while enjoying a very special meal.
Send another question if you need more information about these or any other options for your Walt Disney World vacation, Wendy; we love to help!