That would depend on a couple of things.
First, the booking period for that code has expired. They may not allow you to book more days based on that alone.
Second, if they do allow it, there would need to be rooms that were still available under that code at your resort for those dates.
If those two things come together and you have a CM who knows how to do it, you should be able to get your 2 additional days. It may take a couple of calls to get an answer but it would be worth the try.
Good luck!