The Disney Cruise line rarely releases any sort of discount, and when they do, it is usually limited to Florida residents or another small group, which I never seem to be a part of. The one discount they do release on a regular basis are the Magical Rates. These are specially priced category 12 staterooms on selected cruises are aren’t selling as well as Disney would like. These Magical Rates are usually only available for a limited time, and the number of staterooms that are offered are limited, so if you happen to see one for a cruise you want to go on, grab it and ask questions later.
Remember, category 12 staterooms do not sleep 4, but you can book them with a party of 4, and you will automatically be upgraded before you arrive to a better stateroom. You can read more about it here:
MouseMisers will keep an up to date list of available Magical Rates and dates on the Disney Cruise Discounts page. They are updated weekly (usually on Monday), so check back to see if rates have been released for your dates. If you have already book a Disney Cruise, and a Magical Rate comes up for your dates, you can switch by calling Disney Cruise directly, or your Travel Agent.