Originally Posted by
pinniped
Your first step would be to find a Southwest flight that you want to take prior to the expiration date. Then, during the purchase process, you'll be able to apply travel funds. You can use your travel funds + a credit card if the new ticket is greater than $98. But you'd actually need to fly this one: you can't use this as a trick to perpetually extend credit.
Depending on your exact expiration date in September, you should be able to find some decent fares and destinations...
I'm not sure how exactly AS handles upgrades that later get canceled. Might be a question for the similar thread about AS. When I've upgraded AS in the past, I've fully upfared to first class to get the EQM bonuses. (This often costs little or nothing more than a kiosk F upgrade.) But that shows as a real ticket purchase and wouldn't trigger the AMEX credit. Premium (their version of E+) probably works differently but I haven't personally done it. If you could get the funds dumped into your AS wallet, that would probably be the best bet. But at some point you'd have to actually fly Alaska. (That's not a bad thing...just a limited route map.)
For your 2021 credit, why not just find a couple Southwest tickets for later in the year that fit your needs? It's July now - not like you need to do anything crazy to get your $200-250 for 2021.
I had a prior AS upgrade that was cancelled. In that case, Alaska refunded the amount to my Amex Platinum and my prior credit was reversed.
I recently took a flight to New Jersey with seat upgrades and moved that to a new flight to Alaska. They said they could send me a check for the amount I paid for the seat upgrade, as per my request, as I was concerned about another reversal. However, they did not send a check, but instead credited the upgrade right back to my Amex, which I did not want. Fortunately, so far that amount has not been clawed back.
In the first example, the upgrades were cancelled relatively shortly after booking. In the second example, the upgrades were refunded a number of months after the booking, so that *may* make a difference.