Just had another, simpler idea for this issue. What if during that moment of Ben trying to heal Rey, we cut to Leia’s body disappearing back at the Resistance base? The implication could be that a little bit of Leia’s life Force was still in this world, like when she communed to Ben through a vision of Han, but she gave that little bit of life left to ensure Ben wouldn’t die in the healing process. Would that be too vague? Maybe we could hear Leia whisper something to Ben?

Dom, I think you were trying to figure out what to do with that shot earlier. Maybe this could be where it goes. I know that originally the idea was putting Leia’s body disappearing right after the Ben and Han scene to imply it was Leia communicating to Ben. Maybe we could keep that implication by Ben hearing Leia say “Ben” after he throws his saber, which is what prompts him to turn around and look for the source of the voice. You could take the line from where she says “Ben” earlier, during Rey and Kylo’s duel. Maybe you could also use “Son”, then you could use “Ben” and “Son” interchangeably between the two scenes. Though I think that moment of Ben sensing her mother’s death might work better without her saying his name, since it also felt like Leia was trying to distract Ben so Rey could get the upper hand. Without her saying something, it might seem like he is just sensing it on his own.

EDIT: Leia does say, “We can sill save him” in TFA during her conversation with Han. Maybe when Ben is hugging Rey’s body, we could have Ben hear Leia say, “Son, we can still save her”, or “You can still save her”