I found a great blog post from +Michael Fricano II from Edtechnocation about how to reuse a post in Google Classroom. In his blog, he explains how to handle the post in case you forget to select 'make a copy' of the attachments for the students.
He suggested, don't delete the mistake assignment, just reuse the post, and keep 'create new copies of attachments' checked. Once that is completed, then you can delete the mistake assignment.
I thought it would be helpful to share this information with my audience.