Originally Posted by njvandy

In my experience this does not work. Your new flight credit will have the same expiration date as the original one you used to make the reservation.

I have had success filling out the form online and politely requesting an extension from Customer Relations. I even did this on behalf of my wife who has no status. She was granted a 10 month extension until the end of the year with no pushback. It just takes a few business days to process.