Hello Harriet, welcome to Cruise-Chat!
The ship has a laundry service; however, it's not self-service. My wife and I were on a 14 night cruise in April and packed enough clothes that we didn't need a laundry. Some people bring a small container of laundry soap and wash small items in the bathroom sink or shower. There is a clothes line you can pull out in the shower for drying clothes. You can also dry things quickly if you have a balcony by draping them over the back of the deck chairs.
Hope this helps...