The reason is it's taking a bit longer to make repairs after it ran aground last December. Even though the boat didn't take on water, i.e. no split in the hull, it was damaged and they had to replace a huge section of the it..something like 6' or 8' by 16' is what I heard. The process was very time-consuming and expensive. They had to build a big chamber, sink it under the showboat, lift it up to the hull, pump all the water out of it so that it sucked up to the hull and sealed, cut the bad section out of the hull and replace it, welding it inside and out. They're working with half inch plate steel and it has to line up perfectly as they weld it, on top of the fact that the section of steel weighs well over a ton, maybe two. The Coast Guard and Corp of Engineers are keeping a very close eye on what they're doing, like standing over the workers every minute.
Before the accident, they already had planned to do a pretty good remodel of the interior and they went ahead and did that. So...they had their hands full with all that work. It's amazing that they're even going to be ready only a week later than originally planned.