ET was on the set of the highly anticipated Beverly Hills, 90210 reunion series, BH90210, earlier this month and the 48-year-old actress revealed why she decided to return to her iconic role of Brenda Walsh following Perry's death in March.
"I wasn't attached [before Perry's death]... and it wasn't long after he passed that I finally was like, 'OK, yes,'" Doherty revealed of joining BH90210. "I thought it was going to do well with or without me, to be honest. For me, replaying Brenda was something I said I wouldn't do twice and I've replayed her now twice, so I guess I could never say I'm never going to do something again because I end up doing it."
Doherty -- who's set to guest star on Perry's other project, Riverdale, in honor of the late actor -- also spoke of Perry's impact on the hit '90s series, proclaiming that "he was one of the most important parts of 90210."
"For me, I felt like it was honoring him and his memory and what he meant to the audience and the fans and to all of us," she said of returning to the role. "As his on-set family, I felt like it was an important time for all of us to come together to honor him."
As for how the new show plans to address Perry's absence, Doherty revealed that it will "definitely" be spoken about in the series' first episode.
"The first episode very much deals with it," she said. "Luke was such a sort of quiet, subtle, yet dynamic human being that he had a very strong and lasting impact on people. So, naturally, we would have to deal with it."
ET also caught up with Doherty's co-stars, Jennie Garth and Christine Elise, both of whom spoke about Perry's absence and the show's response to it.
"There are moments when it's easier than others," Garth, 47, told ET. "[Addressing his absence is] not something we're ever going to do the right way 'cause it's just too big of an honor to have had him a part of our cast and now to not have him. It's just weird."
Meanwhile, Elise called Perry's death "unbelievably horrible," but also shared that the late actor is "sort of here in spirit" and that "everybody can't help but miss him." As for the specifics behind the show's plan to honor Perry, Elise emphasized the importance of not doing anything "exploitative."
ET's Kevin Frazier also spoke to even more cast members, with Ian Ziering assuring fans that there will "of course" be a tribute to Perry in the reunion series.
"We can't do this show without mentioning that and dealing with it in some way," Ziering said. "It's still really so fresh, it's hard to reconcile. We're all still struggling with that loss."
"He'll be honored in a very respectful way," Brian Austin Green agreed. "But to everybody that's ever met him or knew him, he was an amazing person and he was a blessing for people to have in their lives. And I feel so blessed I got to do what I did with him. That I had the experience that I did."
Additionally, Jason Priestley said Perry was a "beautiful, humble, gentle, kind, thoughtful soul" whose "absence is definitely palpable." Gabrielle Carteris agreed, calling Perry's vacancy "profound."
Meanwhile, Tori Spelling told ET that the cast "miss[es] him every day" and described Perry's absence as "a huge pull in our hearts."
"He will be a part of our lives as a dear friend that we'll miss every day, as well as the show," Spelling added.