You can bank on it that if a film is a mild success in theaters, studios will find a way to exploit the situation and make more money off the concept. The best example of this is the thousands of direct-to-DVD sequels that litter the walls of movie rental stores across the country. Most are pale reflections of the originals.
Every once in a while a sequel comes along that doesn't improve on the first one, but still manages to entertain. "The Butterfly Effect 2" falls into this category. It's both entertaining and thought-provoking at the same time.