I was wondering if the following strategy would allow refunding/extending part of a non-refundable ticket:

I have a cancelled non-refundable ticket expiring in a week. The change fee to book a new flight is $200.

If I use the credit toward a new fully refundable fare and pay for the excess using a credit card, then get a refund on the new ticket, will I get everything back, including the amount of the credit? Or will they refund only the amount paid using the credit card as cash, and the travel credit back to a credit?

I was thinking that I would only be out $200 if they refund everything to the credit card, rather than the entire amount of the cancelled ticket.