I do think that line sounds a lot more convincing this go around and does sound like something that could have been included in the original cut. “Ben, come home.” says a lot more than just “Ben”.

I think it would work great as Kylo was just saying before that neither of them could go back to Leia now, and for Leia to just prove him so blatantly wrong is enough for him to be in shock, “My mom still loves me after everything I’ve done?”. It also makes his discussion with Han about honoring what Leia fought for even stronger.