I'm trying to puzzle out what the easiest method to give a new Theme for an existing wordpress site.

The present website is fairly complicated and robust.

I copied the present site and moved it right into a development server, used Thematic and produced a young child theme then integrated the brand new design. The look and structure is slightly not the same as the present one, some additional icons, features, along with a custom menu too.

My hope was to accept new site and merely replace the present one. Works out the client continues to be adding posts etc. In a nutshell, this content around the old site and also the new site don't match.

SO am unsure really what the easiest method to proceed is? I'd appreciate any insight.

The fundamentals of Wordpress: this content and also the design are separate. Upload the brand new theme also it will not effect the publish/page content, because that's content within the database. The brand new design may display this content in a different way, but that is design, not content. See http://codex.wordpress.org/Using_Themes