Hi Azel,
i suppose it depends on how you organise your rewrite.
If i need to change a character or add a chapter, for example, i will do that as emotionally as the first draft.
I may then do a rewrite/revision going through the whole script checking grammar, sentence structure etc - so this will be more detached.
I will then go through eg checking that each line of dialogue is in keeping with each relevant character - again, in a relatively detached way.
Then maybe i will go through checking plot lines and time lines etc, checking consistancy - so again, detached.
Then i might check chapter structure of the whole thing - once more, detached.
The final read through/revision will look at the whole and this will be emotionally involved.
I'm not saying that this is how a rewrite should be done, but it works for me!
good luck
Casey