How do I refresh a view (or a page) after a new comment has been posted?
Try using Views Auto-Refresh module. 


  A module to refresh a view after a specified time interval. Includes
  advanced options to avoid reloading the whole view, and to avoid
  causing a full Drupal bootstrap at each refresh.


If you are looking for REAL realtime update you should use some server side javascript like nodejs, to push event to the dom. 

also there is nodejs module for Drupal.

A great tutorial