You have a few options for your students to submit a revision in Gradescope after their original submission has been graded:
Extend the late due date
You could extend the late due date on the assignment's Settings page. This way students can resubmit a new file to the same assignment, and then you can regrade it. You'll be able to refer back to the original file and question scores from the student's Submission History. We recommend having the original graded question open in another tab so that you can view each submission side by side.
Have the student submit a regrade request with a file link to their revision
You could have students submit a regrade request and include in it a file link that contains their revision content. Students will need to make their revision content an active and shareable link. To do this, they should create and upload their revision content as a file to either Google Drive, Dropbox, the LMS, or another online drive and then make it shareable. Your students can then copy and paste this link into their regrade request submission. Then you can open and review the regrade request from your end.
Create another assignment and consolidate the grades
You could create a separate Gradescope assignment in which students can submit their revisions and then consolidate the two grades. Once you're done grading the revisions of the new assignment, you’ll download the grades for both assignments on the Review Grades pages and consolidate the CSVs. Then upload the consolidated CSV to your external grade book or LMS.
Create another assignment and adjust the original assignment’s rubric
You could create a separate Gradescope assignment for students to submit the revisions and update their grade on the original assignment. Once all revisions are in, you can bulk download them using Export Submissions on the Review Grades page or just view them online from that separate assignment (i.e. in a separate tab or window). Instead of grading these on the resubmitted assignment, though, you'd just apply a submission-specific point adjustment or adjust the rubric for each student on the original assignment.