Hello. I have been thinking about rewriting the first several chapters of my novel with everything I learned about writing. Am I allowed to submit the new writing as a new fiction and start fresh or should I just replace the chapters in my already published novel?

(Some chapters will most likely be split into smaller chapters)

This is a good question. I'm unsure if there is a right answer, given that I am somewhat new. That said, I can tell you what I still do.

I, too, have had quite a bit of rewriting in my earliest chapters. Instead of starting fresh, I either deleted/changed what I needed or added things to a chapter and pressed Save. 

In either case, I never felt like I had to rewrite to the point where starting over and reuploading felt like the better option. Especially since I was only a week or two into posting, I always figure that new readers will enjoy any changes I make, and I suppose that's enough for me.

With all that said, maximizing views and going for the best possible ratings and reviews is a potential upside to re-uploading. Especially if you got some early-negative ratings/reviews.

Edit* I'd like to add that I do believe reuploading is allowed when changes are extensive enough to warrant it.

If you're just changing the initial chapters, I would edit the existing ones and then put a note in the author's note section of the next chapter to inform current readers of what changed and if it will affect the story going forwards.
Rewrites being posted as a new story certainly happen, but usually that's done with the story either being heavily edited and added to or even outright completely rewritten from the ground up.

I am doing this. Writing half a million words and listening to readers helped my writing. Redoing all my initial chapters now, but just replacing the old ones.

Thanks for the suggestion. I am writing my novels and I want to know do I start a new fiction or replace the chapters and I am glad I found my answer over here. When I was searching for it online, I also found https://casinosanalyzer.com/online-casinos/best-payout website link where I found a lot of sites through which I can easily make money.