Do you have Work Permit holders who decided to pursue their studies and subsequently earned themselves a Diploma / Degree?
If you do have, they might come to you soon on the upgrading of their pass.
Usual processes still stand even for current Work Permit holders. You just have to ensure that you cancel their current Work Permit, before you issue them with a new pass.
Aside, I think it’s good to check if he or she is suitable to move on to another position which warrants a higher pass category, for such will certainly motivate staff and ensure the recognition of a higher education.