While I do not personally use plugins I have seen suggestions to completely unload and reload them. The Lua forum area might have better 411 for you though.
Also, the Lua Code feature is BETA and all Lua plugins are written by other private party developers (not Turbine). Their working or not working is a) not part of the game and b) the responsibility of the Lua plugin developers themselves.
So it's not that unusual for plugins to break. iirc some have permanently broken.
Whoever says “I” creates the “you.” Such is the trap of every conscience. The “I” signifies both solitude and rejection of solitude. Words name things and then replace them. Whoever says tomorrow, denies it. Tomorrow exists only for him who does not seek it. And yesterday? Yesterday is Kolvillàg: a name to forget, a word already forgotten.
The Oath: A Novel by Elie Wiesel