All of the above.
I would keep checking the website to see if you could add Sunday night to your existing reservation. You could also try to book a brand new reservation and cancel the original one. You could also try to change to WL instead of Boulder Ridge. You could call resort reservations and see if they could add the one night to your reservation.
Do you have a package reservation or resort only? It is easier to make last minute changes with a resort only than with a package reservation. There are often available rooms close to check in date, when people with packages tend to cancel before the 30 day due date.