I have heard from someone within the company, that those already working for Jet2 are exempt from doing the initial online tests, as they have already done "similar" when they took up their original positions.
They are however still required to do the assessment day (Interview, advanced compass test, and groupd exercise) as well as the sim assessment of course.
I'm not sure how correct this is, but my source was fairly concrete.
I don't intent to mislead anyone if I'm wrong.