You can apply for a FTV, at which point the FTV will hold a credit for the cash fare, and a credit for the seating fee. You can then use both components towards the new booking, so long as you haven't started travel on the booking. If you paid for the seat fee at the time of booking and didn't have the ticket reissued there would be a good chance the FTV would turn into an EMD which is more flexible. There won't be a change fee, but you are liable for the difference in fare. See the main Rebooking thread for more information and experiences.