Originally Posted by JY1024

OK, so maybe I'm not going crazy...I was gonna say that I feel like I've done what you mentioned: go into the PNR, click on "change," look through the options listed for your existing itinerary. If it's the same price as you bought it, it will show "$0" to change to it. But if the price has gone down, it'll show a "-$" amount. Just make the "change" and trip credit will be added to your wallet.