Norwegian Sun underwent a scheduled dry dock and refurbishment in San Francisco as part of Norwegian Cruise Line's Norwegian Edge fleet enhancement program. Passenger-area improvements included redecoration of restaurants, bars, lounges and other public spaces, along with stateroom modernization and installation of new beds. The project also included technical upgrades and maintenance, which accounted for much of the shipyard work. The refurbishment refreshed existing accommodations and facilities rather than introducing a major new collection of onboard venues.

Norwegian Sun underwent a multimillion-dollar dry dock refurbishment at Grand Bahama Shipyard. The project introduced Moderno Churrascaria, a Brazilian steakhouse replacing Pacific Heights, and updated the décor of all 33 suites. The Kids Crew facilities were improved, and carpeting and wall coverings were replaced throughout public areas. Technical improvements included modifications to the propellers and rudders designed to reduce propulsion power consumption by approximately 6%, replacement of lifeboat davit hooks with upgraded safety equipment, and work on the ship's potable water piping and HVAC systems. The HVAC conservation project was expected to save approximately six million kilowatt-hours annually upon completion, while the piping replacement program continued beyond the dry dock.