There are two ways to get latest version of plugins with our theme package.
1. Update our theme to latest version
After plugins release new version we will do an update for theme to apply that plugins version for customer. So just follow instruction at http://help.king-theme.com/faq/9-how-to-update-the-theme-3f.html
2. Update manual with our package
First, you should download latest version of package on Themeforest from My Download Items menu. Then unzip package.
Go to our theme folder and /[theme_name]/core/sample/plugins/ you can find all our plugins there. Just use that to upload manual or upload via FTP to get new version.
Hope that make sense.