Hi Troy
That is right there is not way to link a certification directly with a competency.
However if you were to link the courses in the Certification to the competency through achievement path or linking the courses then when the Certification expires the course completion would reset so they could re do these .
This in theory would update the competency and the courses require to be done again - are you able to confirm this is how this actually behaves after running cron .
Regards