I’m not experienced with this, but I had a thought. Is there truly a problem with your book or is the issue that it’s not in front of the right readers? For that, you might want to take a look at your cover. Does it look like other covers in your genre or is it sending the wrong message?
For instance, perhaps your cover gives the impression that it’s a literary historical novel rather than a romantic historical? Or a straight paranormal novel instead of a paranormal romance? Does that makes sense?
I’d not only check the cover, but the title, blurb, etc. Maybe it’s not that the book has problems, but that the wrong people are reading it. A thought. I’d love to know what you decide to do.