Longtime Sunshine

Ok. I know, I know. I haven't posted an update on my first attempt at a novel in quite a while. My writing time has dwindled the past two weeks due to a sick wife, then a sick son, then the ever present day-job deadlines.....Ok, fine. Those are excuses everyone has so I'll throw those out the window. I do have a problem that I'm sure everyone else has had but I don't know how to handle it.

My story has....blossomed from the original idea and I want to run with the new concept. It's nothing extremely major but my main character's motivation has changed. I feel like I should rewrite the majority of what I have and shuffle a few things around to make it work. I know, I should just write everything and then rewrite later but the beginning of the story really needs to change. (Plus, I hate the stuff I wrote in the beginning. It's amazing how even a little experience can really make you a better writer.)

I've been debating how to proceed for about a week and it's time I just make a decision and get back to writing. How do you handle a change to your story that affects everything that preceeds your current train of thought?