Say one purchases a non-refundable fare in any given inventory. If later there is another fare of the same inventory, American Airlines will permit the ticket to be rolled into the new fare and the difference in price will either be refunded or collected without change fee. This is provided the itinerary meets the restrictions of the new fare, the rollover is requested within the advanced purchase window of the new fare and the new fare does not specify "rollovers not permitted".

Specifically, I paid for a generic fare in L inventory sometime ago for a friend to visit meet up with me during her spring break. I purchased it well in advance, not to lock in the fare, but because L availability tends to vanish quickly over spring break. Now I find that there is a sale fare in L quite a bit lower than the price I paid. I called American Airlines, requested a rollover into the sale fare and they happily exchanged the original ticket for another ticket at the sale fare. The difference was refunded back to my charge card.

I suppose that fare rollovers can work the other way as well. For instance, if one purchases a non-refundable YUP fare in A or D, can one opt to rollover into a higher refundable fare in A or D? In such event, are the non-refundability penalties carried over to the new fare?