I found that there is a configuration setting that can be enabled which runs the preview mode with the currently logged in user (an authenticated user) instead of the `default/anonymous` user. 

It's called `Preview.AsAnonymous`, and setting this setting to `false` will allow users to preview as the currently authenticated user instead.

Source: [USING AN AUTHENTICATED PREVIEW IN SITECORE][1]

  [1]: https://theagilecoder.wordpress.com/2014/12/14/using-an-authenticated-preview-in-sitecore/