Once you've published content items, all items, their associated documents, and attributes (tags, mapped personas, etc.) can be found in the Asset Library.
Viewing existing assets
On the navigation click on Assets and head to Library. Existing content will auto-populate.
Clicking on the asset will take you to the content item brief.
If you're looking to duplicate the content item and change parts of the draft to re-publish, use the Repeat this item from the actions menu to duplicate the existing asset.