Sorry Ruth, just noticed your question. For some unknown to me reason, HAL will not typically allow a rate to be adjusted on a paid in full booking even if it is not within the penalty period. They have a lot of different promotions with different rules. They frequently run promotions called SWAT rates (usually guarantee status, random assignments) and another that is common called a 5 Day sale promo. When you book one of these rates they're very low cost but have some strings attached. You have to pay in full at the time of booking regardless of the date of the booking. Also on these, they go into full (100%) penalty as soon as they're booked. So if you don't add cancellation insurance and have to cancel for ANY reason (even medical) there is no refund of any portion of the fare, only the tax is refunded (they're required to refund the tax).
This is not meant to scare you away from HAL, they are a great cruiseline and the best fit for many clients. You just need to know that their rules are often differnt from the rest of the cruise industry. Never pay a HAL booking in full unless it's required and always ask if there are any restrictions/special requirements on the rate code you're booking.