Oh, cool! I feel like I should do this, but then I was wondering, is this a normal thing to do to a novel, just finish it, think it over, and then start writing it again? But I can tell the process I took in writing it is haphazard - upon reflection I included some stuff that doesn't need to be there, and I didn't even have a clear idea of who some of the characters were or what the main conflict was when I started. Not nearly as much as I do now.
As you can probably tell from the responses here, yes, this is a normal thing to do. And you've hit on the reason why.
It's something that tends to separate "new" writers from experienced ones, at least in my experience. There are myriad ways to revise--yes, some people "pants" it and figure stuff out as they go, but even that's largely a process of rewriting and revising, it's just the start point is different.
The key is that you go back and revisit the story. Anyone can sit down and tell a story--verbally, prosaically, in song, whatever--to a group of friends. What separates informal storytelling from published fiction is that, if you seek publication, you're seeking to be part of an industry from which people expect entertainment. Polish is part of that. By no means do you have to rewrite outright, though it can certainly be helpful. You do have to find a way to make the story efficient and effective. Writing for readers is work.
I find I rewrite fairly fully at least a couple of times per WIP. Current MS went through 2-3 heavy rewrites, with another 3-4 scattered rewrites where I went after specific chapters or sections--it's possible to look at the story taking shape, realize that, say, you need a whole new plot beat here, and then add it. Or remove 5-6 chapters and replace them with something quite different.
One thing I wish more people would at least try is closing the document and rewriting a chunk--maybe a chapter or so--from memory. You'll remember the important bits. But having written it once, you'll almost subconsciously cut out the extraneous stuff and, simultaneously, discover more. Doesn't always work, but it can break a block and I'll take any tool I can get when one of those hits.