You can have the skills, but you might not have them to the standard that is required by your gym to compete.
Repeating can have its advantages, you will be very experienced in level 6, and will probably have a great season and a good shot at medaling at competitions.
You will be able to spend more time on learning new and exciting skills as you already know your routines, so wont need to spend so many hours on those.
It does not mean you are not as good as other team mates, every hits a snag at different times. We have some gymnasts who take longer to progress early on and then it all clicks and they just fly past the others. We have other gymnasts who just fly through the lower levels and then hot a wall later on. Spending more time in level 6 now, may mean less time in another level later on.