automatically re-number when not deleting rows

Good day everyone!
I have a list of jobs to do in 1 column. In column 2 is the priority of the job. As a job is finished I want to delete the priority next to it and have the priority numbers re-number themselves (2 becomes 1, 3 becomes 2, etc.). These jobs are ongoing, so at some point I would want to go back to the original #1 and call it priority 6, so deleting jobs altogether is not an option, thus taking out the (row-1) ideas.
Any ideas on how I can set the priorities up to re number.

The list is not in order vertically because the priorities are not always the same.

Thanks for the help!