Mmmm, pinpoint exactly what it is you feel is too samey and then work on varying it? Like, recently, I decided I drew people too samefacey, so I went and drew a bunch of heads, concentrating on varying their cheeks and chins and noses and such. Alternatively, scrap everything and start a new style from scratch. There are lots of ways to draw pretty much anything, and a different way of drawing something might work better for you than the way you're currently drawing it, and there's no real way to know that unless you try.