Sorry about your cruise that you need to move. However, to add to Dave's answer, Royal Caribbean may, in fact, be taking a loss on your room. If they can't re-sell the room in the short amount of time before the cruise, and the room goes out empty, even the $200 penalty they could collect from you would mean a loss for them.
The fact that you want to cancel as far from cruise time as you are means you're under penalty for only $200. Had you canceled closer to cruise time, the penalties increase until the total amount of your payment is not refundable.
Are the flights to Miami totally sold out, or are they just too expensive?