The girl made a deal - her services in exchange for theirs. Apparently she was happy with the result, thus they got to have another go.
Good no one remembered to stop Luffy from asking when to send them, apparently he amused her enough that she threw in a bonus.
Now the Straw-Hats are back in their younger bodies, along with Ace(the bonus), Sabo and Law.
Chaos ensues. The timeline is no more.
They will better their past and the Straw-Hat family will grow.
(AN: The chapters were rewritten, thus I am posting the story anew, chapter by chapter. I apologize for any inconvenience. Let me just tell you that the story will be way better from now on.)