The law of diminishing returns applies as Barry Sonnenfeld hacks out a scant sequel to the initially promising sci-fi spoof. Will Smith must again save the human race from oddly-shaped monsters and hedonistic worms, and so restores Tommy Lee Jonesโ€™ erased memories. Lara Flynn Boyle replaces Linda Fiorentino, who bailed. Wisely, itโ€™d seem. Funny in flashes.