How many islands in The End?

It shouldn't figure a problem since the community-run Minecraft Wiki mentions in their article about The End:

These outer islands generate infinitely, topped with a forest of chorus trees that may be harvested for its fruit.

Meaning that the answer to your question is no, your dreams won't be crushed as it does not have an end.

However, should you for any reason still wish to regenerate The End, all you need to do is access your server's files and delete the folder DIM1 (NOT DIM-1), as all informations about The End are stored there and its deletion means it will be freshly generated.