Hi goeun323 ,
Unfortunately, Qualtrics doesn't allow the expiration date of a distribution to be changed after it has been sent.
I'm not sure if your deadline was set too soon, or too late, but a work-around I've used for smaller email lists when my deadline was set earlier than I wanted is to open each non-respondent's survey link shortly before the deadline. Depending on how your Partial Completion settings are set, that will keep those links active for hours or days past the deadline. This obviously is less practical the larger your email list is, but it is possible.
Good luck!