So, you have to make a note of this.
Later on, while washing dishes, you think of something you might want to change in the WIP. Note time!
Do you do this? I've had to keep a notebook while working on edits to a WIP. It isn't quite the same thing as while I'm working on writing the novel. Edits are different. These are bits and pieces that occur to you as you're working along. It's not too late to change anything in a WIP. I've edited out whole chapters, and characters in novels. I did that with my first vampire novel, Vampire Ascending.
I will write the date at the top of a new page each day, and make notes as to what pages need a little added attention. I like to write down where I've ended too, and if there's anything special I need to go back and do on any given page. I'll also make note of having finished a whole chapter--something to celebrate later because editing is really menial and you can get bored fast. I'm in the edits process where I've high lighted words that are repeated too often, or phrases which are signature of my lazy writing. I've posted about this over on Lorelei's Muse, so I won't go into detail here.
The notes will help you keep in mind things that need to be worked in. I actually have a separate notebook on just little things that need to be added to the work. This helps me keep it all in one place. I might have a line that sounds better than one that's already in there, and I have to jot it down while I'm thinking of it or it all disappears with time. Also, this spot might be back in a section I've already covered, or somewhere ahead, and I keep this notebook handy for when I need to refer to it.
Like I've been taught, edits take as long as they take. To tell yourself you'll do them in a few weeks time is really not a good idea. You might submit it for publication, and later think about something you might have left out, over-looked, or something will cause you to have sleepless nights. And I hate sleepless nights! If you aren't going through your work multiple times, then you're being careless. Hopefully a final edit by your publisher, or your own editor, will catch the things you've missed, but don't leave it all up to them to catch. It might be sent back with a note about needing more editing by you. It's a good idea to get your WIP as polished as you can before pushing it out of the nest.