I reincarnated in to my novel

I was just a normal guy who wrote a novel called I Got Reincarnated into a Magical World, and it became pretty popular. But one day, when I was writing the final chapter, someone broke into my house and killed me. When I woke up, I was confused at first, but then I realized I had been reincarnated into my own novel. And to top it off, there were four new characters that I hadn’t created. By the way, the reason I wrote this novel was to gain some experience before writing my main novel, which, if done right, will be ten times better than this one.