How do you seperate beta and production versions of a WordPress Site?

I have developed a new wordpress site, put it in beta for testing and further programming, then rolled it out to production (www.piccexcellence.com). Works great!. Now I want to go back to beta and make changes for the next release. I do my development and beta testing (beta.piccexcellence.com)in subdomains on the host server before moving it to live on the same host server. My question, how do I continue to work in beta when everything now points to production? How do I make changes in beta without affecting the production site, i.e. the wp database for production? Do I have to set up separate databases for beta?

Thanks,
George