To sacrifice my progress to start a fresh from the beginning?

[Sanshin]

This is about martial arts, not work or anything "important".

Basically I started karate over 20 years ago, loved it, graded twice and then quit 🙄 I was 14. I started again (back from white belt) when I was 28. Graded to brown belt and then quit 😩 I started again at 34, kept the brown belt but just seemed to be getting nowhere with it and the instructor was a weirdo so I quit.

Now at 36 I've gone back, different instructor, kept the brown belt but I'm fucking useless. I can't remember stuff, everything is sloppy and crap, I keep getting into trouble, my fitness is shocking and I can't remember the basics so when I'm asked to demonstrate something to the lower belts, I can't remember it so just look like a fraud. I love karate and don't want to quit again but the situation where I'm the shittest brown belt in the world is putting me off.

I have 2 options - keep going at brown belt and try my hardest to remember the other stuff or relearn it or start again, from white belt - relearn everything properly but it would be another 2 years at least to get back to where I am.

What would you do?

Have you asked your instructor about it?
Could you go more often or maybe train at a lower level to consolidate the basic moves?

Can you do 121 sessions it'll probably come back quickly with focus

Hopefully there will be some posters around with martial arts knowledge: perhaps edit the thread title to appeal to them?

Do you still enjoy the actual sport?

Options other than starting again might include private lessons, finding an instructor you like more, doing additional cardio to build fitness.