The 40-year-old actor, who played Sam Tyler in the time-travel police drama for two series, decided not to return for what was intended to be the show's final series.
Speaking to Digital Spy, Simm conceded: "Maybe I was a bit hasty with Life on Mars. I should've done another [series] I think. Maybe one more."
After Simm's departure, creators Matthew Graham and Ashley Pharaoh developed spinoff Ashes to Ashes, which ran for three series and concluded last year.
However, Simm defended his reasons for leaving, saying: "I missed my family and I missed my home. My reasons [for not wanting to continue] were genuine.
"If they'd filmed it in London I would have done [a third series], and then, ironically enough, they did the spinoff in London!
"I saw Ashes To Ashes and I sort of thought we could've worked something out. Anyway, it's gone now. But I think we were supposed to make another series."
> Read our review of Life on Mars's finale in 2007
Simm's new drama Exile begins tomorrow at 9pm on BBC One.
> Read our recent interview with John Simm