Hello Gina! Welcome to the Disney Parks Moms Panel.
When you redeem Theme Park Admission for a Walt Disney World Resort Theme Park, you are sure to have a day of magical adventures, even if you choose to leave the Theme Park for a break and return later the same day.
Theme Park Admission for Walt Disney World Resort Theme Parks that does not have the added
Park Hopper Option grants access to 1 Theme Park for the scheduled operating hours for the entire calendar date. That means that you can leave the Theme Park and re-enter the same Theme Park later that same day.
I am unsure what you mean exactly by entering the Theme Park by 6pm however, I have personally entered Magic Kingdom as late as 9pm with no issues after having already visited earlier the same day.
The only exception to this rule would be on nights when Special Events such as
Mickey's Not-So-Scary Halloween Party or
Mickey's Very Merry Christmas Party are occurring. On these nights, Guests require Special Tickets for the event or are not granted access after 7pm without them, even if they attended the same Theme Park earlier that day with regular Theme Park Admission.
Have a Magical Visit!
~Todd