Looks like “Dancing With the Stars” is getting nervous about keeping things fresh in the 19th season — ABC’s reality competition program just added former cast member Julianne Hough as the show’s new fourth judge.

This is the first permanent major shake-up for the show’s judging panel, which has been a steadfast trio (Len Goodman, Bruno Tonioli, Carrie Ann Inaba) since the show’s premiere in 2005. The other big change to boost ratings came last year, when Brooke Burke Charvet was let go and replaced by Erin Andrews to co-host with Tom Bergeron, a move that got some backlash from viewers.

It all brings to mind the other go-to move from other competition shows, such as “American Idol,” which played the judge shuffle so often that viewers quickly lost interest. “DWTS” producers, though, must be  confident that bringing Hough on board full-time will inject the show with some new energy. It’s also been rumored that Goodman might want to leave sometime soon.

This isn’t the first time “DWTS” has gone the “extra judge” route to gain buzz — last season, the show brought on a bunch of guest judges (including Hough), from Ricky Martin to “Dance Moms” star Abby Lee Miller. (Some went over better than others.) While the show is regularly the most-watched on television, viewership has still slipped since its heyday, when 25 million people would watch a finale. In fall 2013, the show was reduced to airing once a week instead of twice; in the most recent season, about 14 million people tuned in per episode.

And now, Hough, 26, will have a regular seat at the table — and will also be judging her brother, Derek, who returns this season as a pro dancer. In one sense, she’s coming back home: Hough started on “DWTS” as professional dancer in Season 4 and won the Mirror Ball Trophy twice, once with Olympic champion speedskater Apolo Anton Ohno and the next year with racecar driver Hélio Castroneves.

“‘Dancing with the Stars’ has always been a part of my family,” Hough said Thursday morning on “Good Morning America” where she explained why she decided to go back to the series. “That’s where it all began for me, so it just kind of made sense.”

The show launched her to stardom. After appearing in the eighth season (where she was paired up with her ex-boyfriend, country singer Chuck Wicks), Hough left to parlay her fame into a singing and acting career.

Though things started strong, they slipped after a few years. Her self-titled debut country album hit No. 1, though she left the Nashville scene fairly quickly. The downfall began with her last single in 2010, “Is That So Wrong,” which ignited controversy with a racy music video; Hough claimed that CMT wouldn’t play it because she took off too many clothes in the video. The network denied it, but the video was pulled offline and never returned. Plans for a second album lost steam.

Hough also tried out the acting world for awhile, landing leading roles in music and dancing-themed “Footloose” and “Rock of Ages” (both of which disappointed many critics) and even Nicholas Sparks’s drama “Safe Haven,” which did very well at the box office. She also stayed in the tabloid spotlight during a high-profile three-year relationship with “Idol” judge Ryan Seacrest; they broke up last year.

But she’s back to reality TV, which is not too incredibly surprising; she made multiple appearances on “Dancing With the Stars” since she left, mostly to plug other projects. She’s been a guest judge before, and last season, she even made headlines by sharply criticizing famous hothead pro dancer Maks Chmerkovskiy. That’s the kind of thing that “DWTS” producers like.

So, how will she handle judging her brother, Derek Hough, who will be back as a pro dancer this season and tends to win the Mirror Ball Trophy more than anyone else?

Hough swears there won’t be an unfair advantage, nor will she be tougher on him to prove how not-biased she is. “It’s not necessarily about Derek and the pro dancer,” she said. “It’s about a collaboration, it’s the team effort. It’s what they’re doing as a partnership, and really, the celebrity and what they can do to improve each week.”