To Fix or Not to Fix?

Last week, on my epic Tuesday 'Writing Day', I made a startling and unpleasant discovery. As some of you may know, I finished the (very) rough draft of my novel at the end of May. My plan was to spend the summer editing it myself before getting it professionally edited. Unfortunately, that hasn't gone exactly according to plan. Truth be told, I've done a pitifully small amount of work on it thus far. Well, I decided to turn it all around and use my epic writing day to give it a thorough read through, making notes as I went along. About midway through the book I set it down, a frown of dismay plastered on my face.
To fully relate my discovery, I will now delve into deep metaphor (prepare yourselves). If you've ever bought a house, or went looking for one, you've probably toured a fixer upper. You did your walk through, horrified at the abysmal decor, realizing that it needs a ton of renovations. Despite the unfathomable design choices of the previous owners, you begin to see the charms underneath and decide that with a lot of hard work, elbow grease, and a little love it could really be something. It could be amazing.
You put in a bid and get a building inspection and wait for the verdict. When the building inspector comes through and finishes his inspection, he hands you his assessment. There's structural damage. Not only does it need a complete face lift but the bones underneath aren't good.
Now it's decision time. Do you want to take on such a massive, time-intensive and possibly unresolvable project? Or, do you walk away and find something that doesn't need so much work?
This is exactly how I feel about my book. I was prepared for it to be bad, horrible actually. I was prepared to take on massive edits (and it needs it), but as it turns out I have major issues with the plot. And now I have to decide if I want to stick with it, tear it down to the roots and rebuild, or walk away and start a whole new project. What's a gal to do?