1. Download the full theme package from your ThemeForest account / Downloads.
  2. Unzip the package and open the Plugins folder. Now you have two choices:
    1. Either go to your admin, deactivate and remove your current version of the plugin and upload the js_composer.zip from the Plugins folder.
    2. Or unzip the js_composer.zip from the Plugins folder and upload the js_composer folder in wp-content/plugins via FTP. This way you don’t have to deactivate and remove your current version in the admin.