The star's role on the AMC drama was limited last year due to her real-life pregnancy, with her character Betty appearing in just four of season five's 13 episodes.
"I'm in it more [in season six]," Jones told Vulture. "I can only say that, I think. We're halfway done [shooting] - and I've gotten to do a lot of weird stuff."
Speaking about Betty's future storylines, the actress said that she doesn't believe the housewife will "ever be completely happy" - despite leaving philandering husband Don (Jon Hamm) for new husband Henry (Christopher Stanley).
"She's one of those people who's always searching for something else, so even if she finds [happiness], I don't know if she'd recognise it," said Jones.
"It's sad, because Henry's a great husband and a great guy, and he took in her kids, and he's like this kind of perfect guy, and she's still searching for something."
Mad Men will return to AMC with a two-hour premiere on Sunday, April 7 at 9pm. The show's UK home Sky Atlantic will debut the new season later that month.
> Mad Men creator confirms time jump, full cast return for new season
Watch a behind-the-scenes Mad Men video below: