Here are the covered reasons for cancelling for a full refund. If its not a covered reason you can cancel anytime up until departure and receive a 75% FCC (may have been upped to 90%)
1. sickness, injury, or death of yourself, a traveling companion or members of either of your immediate families, which is diagnosed and treated by a physician at the time your cruise vacation is terminated;
2. involvement in a traffic accident, en route to departure, that causes you to miss your cruise;
3. your home is made uninhabitable by a natural disaster such as fire, flood, earthquake, hurricane or volcano;
4. you are called into active duty by the military to provide aid or relief as a result of a natural disaster;
5. subpoena or being called to serve for jury duty.