Originally Posted by
paterwdb
Is this true specifically because it is a refund? Because when I've canceled a non-refundable after taking the outbound, I've been given a credit for the remaining segments (typically half the fare paid, not the fare minus the one-way published fare). If that is true, it would make sense to book it as non-refundable and take the credit.
No, the same rules apply to all voluntary changes.
However, as others have noted, it is reasonably common for a reprice to not be a dramatic difference.