Not normally, if you want to be sure consult the nurse at your GP practice just in case there is an issue on an island you will visit but if you don't drink there tap water, avoid ice in your drinks unless you are sure it is from a safe source and use any other hygenic practices you would normally do at home. i.e toilet you should have a great cruise some lovely islands to visit.
I have visited the Caribbean many times (cruising and not) and all I have ever needed is a tetanus booster.
Call your doctors surgery, they have your medical history and can give you proffesional medical advice,
it's free and it will put your mind at ease. Have a great time.