In order to help you out, what dates are you going? & what hotel? okay depending on that, Yes they do charge for upgrades. Your best bet is to call Universal & speak w/ someone.
I've had plenty of free upgrades, you dont always have to pay for it. Upgrades using the Loews program have an order depending on your level. Anyone can ask for an upgrade. Off season would be your best bet for a free upgrade. The type of room you book and at what hotel makes a difference too.
It never hurts at check in to ask if there are any available upgrades.