@SkyRaiderG7 They used that time to prepare the Millennium Falcon.
And Luke is the same guy who abandoned them some years ago. So him dying doesn't change their goal, he inspires by showing bravery to stand up and they'd be even more motivated not to waste his sacrifice.
Is how I interpreted.
@SkyRaiderG7 He didn't die for no reason though.
He sacrificed his life to help Leia and others to escape.
Who later won against the First Order.
He basically had the role of Kenobi in episode 4.