1. You CAN upgrade a fully-used-up ticket.
The LATEST you can do so is before close of bushiness ON the same day that you used that ticket's last asset.
2. It doesn't matter where you choose to do the upgrade, because of the great amount of random chance of just
which CM you will encounter at any given day, at any given time, at any given ticket booth or Guest Relations.
Just be armed with the exact cost that you know is the correct upgrade price.
Just ask for your original ticket back and don't accept the deal if quoted some other amount.