Jennie,
The answer to your question is yes, you can leave the park and return later in the day.
One of the things I love about visiting Walt Disney World is that we don't have to feel chained to a park all day long. Our family always breaks in the middle of the day, returning to our resort for some pool time, perhaps a nap, or some other opportunity for relaxation. It keeps us from getting exhausted throughout the vacation, and lets us recharge our internal batteries for our evening return to the park.
QUICK TIP: Since you are considering leaving midday to return to a park later in the day, think about some of the great dinner venues that exist at resorts near some of the parks. If you are going to return to the
Magic Kingdom for the evening, think about dining at the resorts along the Monorail. You could meet Mickey and friends at
Chef Mickey's. Perhaps it is time for the fun Polynesian vibe at
'Ohana. There are also several options at
Disney's BoardWalk before heading back to
Epcot or
Disney's Hollywood Studios. Opportunities abound!
Write me back if you want some custom tailored dining or activity suggestions near whatever park you are returning to for the evening!
Have a Magical Vacation!
Doug