Hello,
You need to update your theme.
Make the full backup of your site. Navigate to Appearance > Install plugins and update.
If you cannot do it automatically, do it manually:
1. Upload the recent version of the theme from Themeforest account.
2. Navigate to Plugins and deactivate the current plugin, you will see “Delete option”, delete the current plugin
3. Upload the plugin archive from theme/inc/plugins/js_composer via Plugin > Add new > Upload > install > activate
Best Regards