I imagine if it wasn't enabled from the start, you'd need to replay it in order to enable more plugins, but @deathwing would probably be more knowlegeable here than me.

I only run a regular witness node, so I have not enabled any extra plugins. Also, if this is your regular witness node I would not recommend adding additional plugins as it may make you miss blocks if it is hit with a lot of requests.

If you disable the plugins (that you added) it should run again afaik.