Welcome to planDisney from a fellow Georgian, Alexandria!
If you are not one who likes "Singing in the Rain", and would rather sing "Rain Rain Go Away," I completely understand why you rescheduled your magical day.
Before you can rebook your Disney Park Pass system reservation you will need to change the
valid date of your ticket in your
My Disney Experience Account.
Once you log in, go to "My Plans." Scroll down beneath your planning party and you will see a blue button that says "Tickets & Memory Maker." After you click on that, you will see your individual ticket along with a button that says "Change Ticket."
Once you click on this "Change Ticket" button, you will be able to change your ticket's valid date, pay any applicable fees, and even add the
Park Hopper Option. After you change the date, you should be able to make your
Disney Park Pass system reservation, pending availability, of course.
If this still won't work, do not let this rain on your parade, you will just need to call the Ticketing Cast Members (407) 566-4985.
I hope that this answered your question, Alexandria! Please come back here if we can answer any other questions for you.
Stay dry!
Sarah B.