Sorry, didnt see this original question. I had this exact same question and experience, so I called royal Caribbean directly. They told me that the refund should happen automatically, with the normal processing time that royal takes (3-5 business days I think). And if didnt happen I should call back to make sure that the refund happens. I also asked if I found out within the 48 hours of leaving for the cruise. They told me same thing applies no matter when I was notified of the upgrade, and I should go to guest services while onboard if I didn't receive the refund right away.
So basically be prepared to have both or double charges on your credit card until everything is cleared up. This is because the upgrade is an automatic charge once your bid is accepted.
I'm currently in sky class awaiting to hear back about my upgrade. I'm 7 days out from my cruise and I haven't heard a thing, I'm sure we wont be upgraded at this point but we're still in the running. ??
Hope that helps!