You can export and import using the Explorer client (/alfresco), but that means you will lose the version history and some, but not all, metadata. Tags are lost, but not Description and Author for instance. Also, all imported documents will be owned by the importing user and the created and last modified dates will be set to the import date.
It probably won't work to export the entire site space, it's better to export each part of the site (the document library, the blog etc) by itself, then you create a new site with the same name, after you've cleaned out the db and content, and import your files (and wiki and blog pages, which are also files) into the new structure.