LEAH REMINI is trying to bury the hatchet with Katie Holmes – but only because she needs the “Batman Be­gins” beauty to help boost her payday for the anti-Scientology book she’s writing, say sources.

Although the women have both cut ties with the controversial church, insiders say Katie has “never really liked Leah” and has no intention of helping with the book. Without Katie’s name on the project, sources say the former “King of Queens” star won’t get the big-bucks advance she was looking for.

“Leah’s heard offers upward of $5 million to write this book, but publishers know her name alone isn’t going to make it a blockbuster,” a source said. “She’s been told she needs to get Katie to contribute by relating her feelings about Scientol­ogy and backing up at least some of Leah’s charges.”

Leah, 43, publicly split from Scientology in July over disagree­ments with the church’s policies and leadership. Katie, 34, ended her association with the cult-like organization after splitting from Tom Cruise – the church’s most famous member – in June 2012.

So far, Leah, who ended a 10-week run on “Dancing with the Stars” on Nov. 18, has found Katie to be an un­willing dance partner when it comes to the book. “The two of them have a history, and not always the best kind,” the source said. Leah’s sister Nicole claims that in 2006, Katie reported Leah to church leaders for causing a stir about her assigned seat at Katie and Tom’s wedding. And things apparently haven’t got­ten any better since then.

“But Leah’s determined to win her over,” the source noted. “She knows she needs Katie to help her push this project over the top