The threat of sequelitis strikes "Neighbors 2: Sorority Rising" almost immediately. Offering a key gender reversal—a hard-partying sorority rather than fraternity moves next door to parents Mac (Seth Rogen) and Kelly Radner (Rose Byrne)—the film is otherwise little more than a stale, less inspired redux of 2014's very funny, unsuspectingly sweet "Neighbors." Returning writer-director Nicholas Stoller (2012's "The Five-Year Engagement") and co-scribes Andrew J. Cohen, Brendan O'Brien, Seth Rogen and Evan Goldberg appear to be going through the motions. There are individual nice moments, to be sure, but it holds less than half the laughs of its predecessor and gives that picture's secret-weapon standout Rose Byrne (2015's "Spy") disappointingly little to do as she is frequently sidelined by her character's pregnancy.

With their family only a few months away from expanding, Mac and Kelly are looking to sell their home and upgrade to something bigger. Before they can do so, however, they face a one-month escrow period. The prospect of their new buyers dropping in unannounced for inspections doesn't seem so bad until new renegade sorority Kappa Nu, led by freshman Shelby (Chloë Grace Moretz), moves into the old frat house next door. When a civil request for them to curb their partying for 30 days fails miserably, their troubles are only exacerbated by the appearance of former alpha-male frat president Teddy Sanders (Zac Efron), who has finagled his way into the house in exchange for his experienced mentorship. A new war between neighbors is about to begin.

"Neighbors 2: Sorority Rising" opens with the newly pregnant Kelly throwing up, mid-coitus, on husband Mac's face, a cheap gross-out moment more forced than believable. It is a harbinger of the lesser material (involving dildos and used tampons) yet to come in a film that continuously makes the case for why a follow-up didn't need to be made. There are slight differences in the sorority gals vs. the frat guys from the first movie—the ladies, for one, have had it with being objectified by the opposite sex and are also not as quick to comingle with thirty-somethings Mac and Kelly, who they view as old—but this is pretty much a loose beat-for-beat repeat of its predecessor. What is missing is the freshness, charm and truth of the relationship between Mac and Kelly, who in the earlier movie were at a crossroads between their adult responsibilities and a desire to sow the last of their wild oats. Telling, heartfelt observations are in short supply this time as director Nicholas Stoller hits broader, commonplace beats.

Seth Rogen (2015's "Steve Jobs") and Rose Byrne (2015's "Spy") continue to make for a likable romantic pair as Mac and Kelly, but there is something irksome about a screenplay that saddles its female lead with a pregnancy, robbing her of the chance to participate in a lot of the physical hijinks in the story. Furthermore, whereas Kelly was pro-active and savvy before, here she waits for the men to put their plans into effect. Zac Efron (2016's "Dirty Grandpa") is quite engaging as Teddy Sanders, once the resident BMOC who, following graduation, has had a tough time finding his way in the adult world. The three-dimensional treatment of his character is appreciated; he is a nice guy overall and refreshingly accepting of all his friends, but can give as good as he gets when he feels he has been disrespected. Chloë Grace Moretz (2014's "If I Stay") brings a comedic spark to the ultimately frustrating Shelby, whose desire to make friends sends her down a path from which she learns very little. She, like Teddy, is developed enough to be more than strictly a villain, but she is also so naïve and frequently tactless in her treatment of others it is difficult to like her. Popping up far too briefly is the forever-welcome Lisa Kudrow (2010's "Easy A"), reprising her role as forthright Dean Carol Gladstone.

A stench of obligation permeates from "Neighbors 2: Sorority Rising." The film is not by any stretch a complete bust—Mac's unlikely friendship with Teddy is surprisingly sweet, as in a moment where they cement their bro bond through a lingering bear hug—and there is at least one hilariously wrong one-liner where Mac discusses having a Jewish baby. Also of note is the fair, sympathetic handling of Pete (Dave Franco), Teddy's gay, newly engaged best friend. For once, a major studio comedy has featured a gay character who is treated respectfully and as a regular guy, his sexuality used neither as a punchline nor a point of ridicule. Unfortunately, "Neighbors 2: Sorority Rising" too often plays like a familiar, faded knockoff of the original. With nothing new to say and only a handful of earned chuckles, all involved might have been wise to leave well enough alone.