Which ship will you be sailing on?
Only the Pride of Hawaii will have self service laundries aboard. If you're sailing on it, you will not have to pack as many clothes. The other ships will have a fill a bag 50% laundry sale at least once during your cruise. Or you could use the ship's laundry on the other days a full price to reduce the number of clothes you need to pack.
I would pack half the clothes you think you'll need. Therfore, on a seven day cruise, 7 outfits each should be enough along with the outfit you're wearing on embarkation day. Don't forget to pack casual clothes for the day and resort casual clothes for the evening. Depending on how active you are, you could possibly get two days of wear on some outfits. Then use whatever laundry there is aboard your ship to get more days of use.
Other items you might wish to pack are:
Rain gear, which we all hope you will not need, but always wish you had.
Nightlight if you've booked an inside cabin.
Camera for photos.
Highlighter for marking up your Freestyle Daily.
Binoculars for viewing the shore.
Basic toiletries, razors for men, makeup for women, toothpaste, toothbrushes, etc. You will not need to pack soap products, as they are provided.
Electronic devices with their batteries or chargers.
Birth certificates, driver's licenses, or passports.
I'm sure others may add more to this list, but don't forget, the more you pack the heavier the bags get.