Been there, done that, got two t-shirts.
First time, I wrote a 76,000 word book in first person. Finished the book, found AW, read the forums voraciously, decided the book needed maaaaajor rewrites. Went through the whole thing and tore it up, dumping entire passages and inserting more all the way through.
A couple of months later, after still more research and studying, I decided that the book would be much better in omniscient third person than the first person it was in.
Yes, I went through the entire (now 82,000) damn thing and changed every single I, me, and myself. I thought my fingers would fall off.
But ya know what? That second rewrite I found still more things that needed fixing and improving, so even though I was supposed to only be changing the POV, I ended up editing in a major way, and my book is miles better for it.
So yeah, it's a lot of hard work. And it's daunting and exhausting and frustrating. But it is work well worth the finished product.
You kin do eet!