Hey there, Rebekah! Thanks for stopping by planDisney with your question.
Rebekah, your question is kind of a two-part answer - yes and no. You can change your
park pass reservations but you can't swap them with another day perse. To change your park pass reservation, you actually have to cancel the existing one first. Then, you can go back to the park pass reservation website and make an all-new selection just like you did before. But, depending on the availability, what you are wanting to switch to might not be there anymore. I'd suggest before canceling anything, to take a look at the
Walt Disney World Theme Park availability calendar to see if the switch could actually happen or not. If it can, I'd go ahead and cancel your existing park pass reservations and make your new selections. But, if not then you'll just have to stick with what you already have.
If you are worried about the crowd levels being high due to the Annual Pass preview that is going on that day, I wanted to let you know that Annual Passholders will also need to have park pass reservations for that day. So Epcot won't really be any more crowded than it is already going to be if that makes sense. Also, the previews span almost the entire month and being that spaces out, you won't really notice a high impact on the crowd levels while you are visiting. Also, Epcot is really big and can fit a lot of people nicely with space to still walk around. Even on some of the busiest days of the year, I don't find Epcot to feel overly crowded because everyone is so well dispersed. If you aren't able to move your park pass reservations around, I wouldn't worry about it too much. You guys are still going to have a really great day.
I hope this helps, Rebekah. If you have any other questions before your trip, I'd love to help. Please feel free to stop back by and
ask me. Have fun!