A Question for the Poets - Do you revise/change your original work?

Poetry for me has always just flowed. And I have always felt that a true poem written by me, is the original one that flowed when I first sat to write it down. Sure I have gone back and re-read later but once it is out, that's it. Not like a novel or short story that needs to be tweaked and changed fifty million times before it even begins to be right.

I have always felt that the true nature of the poem can only be captured in that one sitting, when it is first written, later on you won't have the feeling/inspiration/thought process that first spurred you to write it.

Lately though I have been reading some of my old work and have found a couple of missed beats. I'm not a free verse writer, I am meticulous in rhyming and rhythm, but sometimes, when I just want to finish something off I will stick a word in that if said a certain way can be right, but not really.

So now I have a dilemma, go against my belief of "first draft is true draft" and go with "three years down the track I thought of a better line that could fit in there"

So do you ever change your poetry after yo have first written it? If so, how much is too much. I don't want to change the vibe of the poem, which I think is why I'm so scared to change any part of it, in my head, it will cease to be a feeling, and just become another bunch of words on a scrap of paper.