The best way to handle Leia’s death would be for it to happen before Episode IX even begins, and the best way to do that would be to have a time-jump. Actually, a time-jump could solve a lot of problems with the new trilogy.
Recall, there was a time-jump between both A New Hope and Empire Strikes Back, and between Empire and Return of the Jedi. This time jump allowed the characters to grow and for various things to occur off-screen that helped make the stories make sense. For instance, the Empire was able to rally after their stunning defeat in Episode IV in the intervening time that we don’t see, helping to explain why they’re so strong still even after losing the Death Star.
Luke is also able to go and train off-screen before Episode VI, helping him grow into a more powerful, confident Jedi and allowing him to instantly be older and more experienced than he was in Episode V.
But Episode VII and VIII pick up right after one another thanks to the former’s cliff-hanger ending. This time a time-jump could help with lots of things, like give Rey time to go study the Jedi texts and train, build her own lightsaber (see above) and so forth. It could also position us in a cool new planet with a new rebel base and so forth, and help give the writers a better jumping off point for the film with various stories already underway. We didn’t have to see how Leia, Chewie and Lando formed their plan to rescue Han Solo, or how Luke trained and RotJ was better for it. The same applies here.
REF: Erik Kain. Forbes.com