When your website has been already imported to Site.pro, before Publish:
Recheck SEO of each page. Check that Title, Description, Keywords, User friendly URL etc. field are filled;
Recheck if main keywords appear in each page content. Use keyword variations and related terms on the page to avoid repeating the same phrases over and again.
When the SEO setup is done:
Publish your website;
As the website code changed, you should republish your website to Google console (Google take the imported website as completely new one).
NOTE: If the SEO Ranking won't change, please inform Site.pro support, our team member will analyse this issue and provide some tips to improve it.