Playbooks is automatically updated within hours of a new version being available - generally there is nothing you need to do to get the new version. The update is applied when you log into the Playbooks extension.
In rare circumstances, you may need to update the Chrome extension:
- Right click the Playbooks extension in the top-right of the Chrome browser window
- Select 'Manage extensions'
- Click on 'UPDATE' near the top of the page