How often does Carnival add new excursions?

Cruising in November to western Caribbean and read their are two fairly new dolphinariums in Grand Cayman. Already have my excursions planned for other ports but none for Cayman and would really like to do the dolphin encounter. The problem is that neither place will offer a refund if we do not stop in that port. I've learned from reading the boards (thanks to all you helpful people out there ) that it is not uncommon for the ship not to stop at GC due to rough seas. So this is definetly a concern. I'm hoping if Carnival offers the excursion and I book it through them we will at least be able to get a refund if we skip GC. I know it will be a little more expensive booking through CCL but I'm willing to pay it...kind of like "cruise insurance." After all its over $100 pp x 4 pp is quite a chunk of $$. So...does anyone know how often they update or add new excursions?? I have read on that many of the other cruise lines are already offering the dolphin encounter in GC. Hoping Carnival does before November. Thanks for any info anyone has.

No set timeframe for when they add excursions. Only for when the excursions for a certain sailing are added. Currently Carnival does not do a dolphin encounter on GC. Maybe they feel it's too much like going to a prison and wanting to play with the prisoners.