As a goodwill gesture for a cancelled flight, I received a $200 "trip credit" issued on February 1, 2022. By it's terms, the credit expires one year from issuance. I assume I could buy a ticket now with this trip credit for travel next (say) November. If, I decide not to take that flight and cancel it, do I get a new trip credit with a later expiration date? In other words, can I extend the life of this trip credit by buying a future date and then cancelling it?