What was once old is becoming new again on the small screen. Some old shows, like “Starsky and Hutch”, “Dukes of Hazard” and “Miami Vice” transitioned over to the big screen, but now there is a new movement in television to resurrect shows in an updated format.

One of the most well-known remakes is “90210”, which stems from “Beverly Hills, 90210”. A few of the original cast members, including Jennie Garth, Shannen Doherty and Tori Spelling, all returned as their former characters.

So how do two shows with basically the same premise differ? For starters, the original focuses on a group of rich kids attending West Beverly Hills High School, while the remake shows how a family adapts to the same school after moving from Kansas. The general themes of the episodes overlap, but in the new show technology increases drama.

In regards to ratings, the 1990-2000 series brought in an average of 14.42 million viewers in its 10-year run, according to Entertainment Weekly. Its first season pulled in 14.8 million. Although the 2008 version is still in its first season, it has a much smaller audience with an average of 3.12 million viewers, according to the Nielsen Ratings.

Another show which is about to re-debut is “Cupid”, which initially premiered in 1998 and lasted one season. Rob Thomas, best known for the short-lived “Veronica Mars”, is redeveloping his original show to air on ABC beginning March 31. The plots and character names of both shows are virtually identical, although there is an entirely new cast, including Bobby Cannavale (“Will & Grace”) in the starring role, replacing Jeremy Piven (“Entourage”). “Cupid” is the story of a man who believes he is the reincarnation of the god of love. Interestingly, Rob Thomas is not new to reworking TV shows, as he also works on “90210”.

Unfortunately, bringing a show back from the dead does not promise success. “Knight Rider” (1982-86) was revived for the fall 2008 season only to be cancelled after 18 episodes on February 25, 2009. The original show averaged approximately 7.5 million viewers, according to IMDB.com, but the new show has just 6.1 million, which is still not good enough to remain on the air.

Remakes may be good in theory, but ratings show they are falling short of their predecessors. What it comes down to is that numbers don’t like, and sometimes networks have to pull the plug…twice.