This can be a bit of a minefield - If you find a dojo that is of your style, obviously no problem .
There are many dojos that will insist no matter your grade, you will need to go back to white belt (beginner).
A firiend of mine with 25 yrs experience recently joined another organisation - they insisted that he and all of his students go back to white belt.
Personally I accept all grades - I have never ever demoted a student - I have had several students after a a couple of practice sessions ``ask`` to be demoted.
Just take a good look around before you commit yourself to another dojo. play it by earole.
Co-author of "Positive Aikido"
Aikido Controversy - https://www.youtube.com/watch?v=FMuDqKOjnls