LOS ANGELES – “17 Again” is one of those movies that requires you to suspend all disbelief and assume that someone who looks like Zac Efron could, in 20 years, turn into someone who looks like Matthew Perry.

(Those must have been some rough years – either that or Rob Lowe wasn’t available.)

Can’t do it, you say? Well, that detail is just about as implausible as the film’s premise itself: Mike O’Donnell (Perry), a miserable father of two on the brink of divorce, gets a chance to relive his high-school days and improve his future by becoming 17 in the present day, all thanks to the magical powers of a mystical janitor (Brian Doyle-Murray).

It’s always some odd figure on the fringe who brings about this kind of fantastic transformation, isn’t it? This guy literally says to Mike: “I bet you wish you had it to do all over again.”

Well yes, there are a lot of elements in “17 Again” that feel awfully familiar. Director Burr Steers, a long way from his darkly comic, coming-of-age debut “Igby Goes Down,” takes you places you’ve been before, many times, in more charming movies like “Big,” “13 Going on 30,” “Freaky Friday,” “Never Been Kissed” and even “Back to the Future.” The idea of going back to high school is so overdone, there was even an entire episode of “Family Guy” that parodied it. (Jason Filardi is credited with writing “17 Again.”)

But rather than changing his decision to abandon his dreams of basketball stardom and marry the girlfriend he knocked up, Mike realizes his true purpose is to reconnect with his wife, Scarlet (played as an adult by Leslie Mann), and teenage kids Maggie and Alex (Michelle Trachtenberg and Sterling Knight). The result is facile and feel-good, not engaging or insightful.

Efron maintains the dreamy presence that made the tweens scream in the “High School Musical” series – those eyes! those cheekbones! – which is on full display when Mike-as-adult-as-kid gets a makeover from the K-Fed get-up he initially dons in a feeble attempt at fitting in. He steps out of a Porsche, purchased by his nerdy childhood best friend Ned (Thomas Lennon of “Reno 911!”) who grew up to make it big as a computer geek, and with his aviator sunglasses and devil-may-care shag haircut, he looks like … well, he looks like Zac Efron. At least Steers knows how to capitalize on his star’s strongest attributes.

Efron also enjoys a couple of amusing scenes here as a grown-up delivering uptight diatribes in a boy’s body, and he connects with Mann in a way that surprisingly isn’t all that creepy. But he still seems too pretty and lightweight to be a persuasive leading man capable of carrying a film. It’ll happen, though. There’s time.

It certainly doesn’t help his cause that he’s been given such a cliched depiction of high school life in which to function. The jocks (the leader of whom is conveniently dating Mike’s daughter), the nerds, the awkward cafeteria moments and an out-of-control house party – they’re all there, with nothing new to give them fresh life.

It makes the singing-and-dancing hijinks of the East High Wildcats look downright subversive by comparison.