Hi Mary Ann. There is an extra charge for sodas, including at mealtimes. Typical price is around $2.00 per can, which includes gratuity. NCL offers a soda card for adults for roughly $60 for a 7-night cruise, but it's not worth it, IMO, unless you drink a lot of soda.
There are many ways to cut costs on an NCL ship or any other line as far as soft drinks are concerned. Lisa is correct that all soda products cost money. The typical charge is $1.75 for a full can of Coke related products + a 15% auto tip. Always request canned soda, rather than in a glass of soda from a bartender. The glasses are filled with ice and the overall content of soda is about 6 oz's vs. a can at 12 oz's. Go lightly the first day or two, then when at a port, I suggest that you BUY a 6 pack of plastic 20 oz. sodas in the port that you are at. Usually you will port 4 times on a 7 day cruise, which gives you lots of opportunities to buy a 6 pack here and there. The room steward will supply you with ice. Otherwise, breakfast drinks, like orange juice, grapefruit juice, apple juice, hot coffee, hot tea are available during the buffet hours at no cost. So if your a conservative cruiser and look for the free drinks as mentioned above and buy a few 6 packs during the cruise, you can get by very inexpensively. NCL has no problems in bringing back a small quanity of soda from offshore. They won't allow beer, wine or hard liquor to be brought aboard to be brought back to the stateroom. They will hold the liquor until the end of the cruise. If you are a family of two or more, then each could bring a six pack back on board. I always suggest the deposable plastic 20 oz. drinks. Bottled water has a typical cost of $3.50 to $4.00 for a 31 oz. bottle. The water on the ship is very clean, and very good. Save a empty 20 oz. coke bottle and re-fill it with ship water, and keep on ice. Most bottled water in the US is from a municipal water sources that has been reverse osmosis anyway. Just a few ideas to save some big bucks especially if your large family or heavy soda drinkers. I really don't suggest the coke package at $50.00 or so for the cruise. The container is rather small.
Enjoy the trip, welcome to Cruise-chat.com it's a great website with lots of knowledgable cruisers on board.