Hi,
Both Visual Composer and Revolution Slider plugins are themes bundled based. This means that you can update them only to the version launched with the theme.
To update your theme-bundled plugins, please follow the instructions :
1) Make sure that you are using the latest theme version ( if no, please update );
2) Go to plugins and deactivate/remove them;
3) Install/activate them from theme required plugins (dashboard notification);
Regards,
Michael