No, if you want it to split out between going back to a credit and the difference to the credit card, then it has to go through refunds which takes 7-10 business days.

If you want to use the ticket value including the additional you added from your card, you can call and then can get the "refund request" (24 hour cancel) denied, which will turn that ticket back into a FFC available for immediate use, but that won't send money back to your card. If your new ticket is then less than the cancelled ticket, it would issue you a new credit for that difference (though if the new ticket is more than the original credit, you could theoretically ask the agent if they would be willing to designate that difference as refundable [since it was under 24 hour flex booking policy] and send it back to the credit card but that would very much be a policy exception, not something to be relied on).