Dodgeball star Long appeared in three episodes of the Fox sitcom as Paul, a love interest for Zooey Deschanel's Jess.
"I know that Justin Long might be coming back, and we didn't think he would," Johnson, who plays Nick, told The Hollywood Reporter.
However, Johnson suggested that Lizzy Caplan, who played Nick's girlfriend Julia, is unlikely to return.
"I doubt it - especially because she just got on a Showtime show [pilot Masters of Sex]," he explained."It's really unfortunate, because I think she's so good to act with. But you never know."
Dermot Mulroney was recently cast in a recurring role on New Girl. The J. Edgar star will play Russell, a wealthy older man who dates Jess.
New Girl continues on Tuesdays at 9/8c on Fox. The series also airs on Fridays on Channel 4 in the UK.
> Big Love star Jeanne Tripplehorn joins Zooey Deschanel's New Girl
Watch a clip from the most recent New Girl below: