Any of your proposed actions could be appropriate, depending upon circumstances.
As a student, you need to understand what you need to improve, exactly what you need to get there, and practice. It's your teacher's job to set you on the right path by showing you what you need to improve, and giving you the tools to get there. Mindless practice does not lead to improvement; practice is a continuous refinement process that requires active adjustment.
If you already know what you need to improve and how, then the problem may simply be motivation. Take a break, and come back later.
If you do not know what you need to improve or do not know how, this is a bigger problem.
- Ask your instructor for more guidance.
- Ask your instructor's peers for guidance. Sometimes a fresh perspective on the same subjects is needed for improvement.
- Branch out or move on to a different school or system. It's possible you have outgrown your teacher.
As a monetary matter, martial arts teachers need to retain students. But in most fields outside martial arts, people expect to graduate at some point. Don't get stuck because it is in your teacher's interest, but not yours.
Rank is a motivation for beginners. In most cases, rank matters only in your head. Many people quit after reaching shodan because they consider their goals met. If you have already reached your goals outside of rank, then why slog through for the piece of paper?
Martial arts can be a lifelong pursuit, but it does not have to be for you.