If you are unsure as to which version of Empirica you have, you can run this line in your app to show you all the meteor packages in the app, including Empirica Core:
As new versions of Empirica become available, you might want to update the version you are using in your app. To do so, simply run:
meteor update empirica:core
Note: you might not want to update your empirica:core in the middle of a project unless it solves an important problem.