When a ship needs a facelift, she goes into either dry-dock for an extensive makeover or will have a retrofit which is basically a quick fix.
According to www.shipcruise.org, it takes 3 years to build a ship but only 3 weeks to a month for an overhaul. For the cruise line, it's a great chance to update technology, make some cosmetic changes or add new restaurants and shops. You can imagine the revenue loss during that time but the rewards will be greater when the public cruises on the "new and improved" cruise ship.
So what's a retrofit? It's a refurbishment basically. Like some cruise ships, they may have cut out a portion of the hull and installed ready made balcony cabins. This is true on older ships especially when there were few balconies on board. They may add something that is on newer ships but lacking on older ships, like the adult-only Solarium pool. It's a great way to appeal to the cruise audience without having to pay for a huge dry-dock bill. Time is money.
Adventure of the Seas, of Royal Caribbean's voyager class, recently went into a retrofit. They added some features found on their Freedom and Oasis class of ships. Giovanni's table, a fee for use restaurant, was added along with new technology. Flat screens replaced the older clunky models of televisions, and some old carpeting was replaced. The pool deck was redone as well as adding a large outdoor movie screen. She was out of commission for about a month and a half. Not bad when you consider the many customers she will lure in.
There are things I wish would have been changed. I would have moved the concierge lounge. It's currently a windowless closet of a room. Oasis concierge lounges have windows and an indoor-outdoor seating. I would have liked to see the furniture replaced as they are outdated and getting worn.
However, beggars can't be choosy and I'll enjoy the upgrades on our Adventure cruise in 2016.