NBC Prods., which will introduce a new cast next fall on its Saturday-morning series “Saved by the Bell,” may not let the “old” crew slip away entirely.The network confirmed a planned prime time spinoff is in the works, “Saved by the Bell Goes to College” featuring series regulars Mark-Paul Gosselaar, Mario Lopez and Dustin Diamond from the web’s top-rated Saturday-morning show. Exec producer Peter Engel will also perform those chores on the prime time pilot, written by “Doogie Howser, M.D.” co-producer Elaine Aronson. The new show would feature the three former students of fictional Bayside High moving on to college together. “Saved” has proved a consistent winner among teenagers — now NBC’s target audience in the morning daypart, countering animated fare on ABC, CBS and Fox — and Gosselaar and Lopez have become teen heartthrobs on the order of the “Beverly Hills, 90210″ crowd. Syndication success Moreover, because the show is produced by the network’s in-house unit, NBC owns rights to the series, which already has proved a success in strip syndication, where it’s distributed by Rysher Entertainment. NBCmay have gotten the idea for the spinoff last November, when a prime time telefilm based on the show, “Saved by the Bell, Hawaiian Style,” performed solidly in a Friday time period, pulling a 9.5 rating/17 share in households and ranking third for the week among all programs among teens. Only one regular character from the existing “Saved” series (Dennis Haskins, who plays the school principal) will be back next season, when the show will be titled “Saved by the Bell: The New Generation.” Engel will continue as exec producer.