Hello, Estephani! Thanks for bringing your question to planDisney!
Unfortunately, if your Magic Key is
blocked out on a certain day, there is no type of upgrade ticket that you can use to access the parks on that day. The only option would be to
purchase a regular theme park ticket and to make a
theme park reservation for that day with that ticket (subject to availability).
If the date you want to visit isn't blocked out, but is showing as no theme park reservations available, I suggest checking back often. Not only are more reservations added to the calendar from time to time, but Magic Key holders are constantly modifying their plans so you never know when availability might pop up. Magic Key holders have until 11:59 p.m. PST to cancel a reservation, so you might even have luck finding a reservation the day before. You can make theme park reservations up to 90 days in advance and, depending on your Magic Key type, you can hold between two and six reservations at a time.
I hope this helps. Have a magical day!
-Linda