You shouldnt HAVE to re-certify unless you have extenuating circumstances although if you've been an inactive diver it is generally a good idea to take a refresher course. If you havent dove for 2 years since your certification it is suggested that you take a "dusty diver" course. They usually run about $30-40 dollars just to refresh your memory about diving. If you've gone longer like say out of diving for 5 years or more you should take a "rusty diver" course. They are usually a little more pricey up into the $100 dollar range. The Dusty diver course just usually takes you into a swimming pool and refreshes the diving skills and helps you remember how to fill out log books and the basics of diving. The Rusty diver course is usually more intense and they usually want you to go through a classroom session, a pool dive and 2 open water dives but usually that is if you havent dove for over 5 years at all.
For me it would be worth it to dive the Caribbean! We have some friends that have dove St. Thomas and St. John and say it was one of the top 10 dives so far and they've dove ALOT!!!
Heidi