Originally Posted by
xliioper
Regardless, if you exchange a refundable fare for a non-refundable fare that costs more, the cash from the original refundable fare is not going to remain refundable.
This is true, and is exactly why it is terrible that the default for "Change Flight" on a refundable ticket is to show cheapest available fares (almost always non-refundable), and not refundable fares. The only way to get "Change Flight" to show refundable fares is by explicitly specifying a fare class for which the cheapest available fare is refundable.