changing theams

i would like to know if changing themas would case my site to drop in search its been gaining speed but i don’t want to loose what little i have also its dam ugly site as far as im concern would like a clean and fresh site to better sell my product and would i have to redu all my hard work in seo? thank you for your time
beameupscotty

https://b-o-o-k-s.com