The local authority can maintain an EHC plan until you turn 25. They will end/close the plan if you move onto higher education, paid work or leave education.
As long as the EHC plan continues, the local authority must continue to review it each year. Relevant services should still be involved in the annual review process.
If you have an EHC plan and leave education but then decide to return, the local authority will consider if the previous EHC plan should be reopened and renewed. This is only if you are under 25 years old.
It is possible that you will have to go through the full EHC needs assessment if there have been major changes.