You are using a theme purchased from author themesflat. you want to update to the latest version for plugins like. Visual Composer, Revolution Slider Please follow the steps below.
1. The first you need sure use theme Latest version ex: At the moment 1.2.1
in the case theme is not update latest version you can use plugin envato kit
2. Deactive and delete old plugin
3. Reinstall according to the link attached in the theme ( We regularly update the latest version to hosting. When there is a new version you just need to delete and reinstall, you will have the latest version for the website )
4. Check the result
if you still not sloved the problem. Please contact skype id: themesflat or email: firstname.lastname@example.org send link your website username pass i will login and check it for you. Thank so much