How to update the theme
You can update your theme via FTP or through the official Envato Plugin. See the information below. The first thing you need to do to update via FTP is re-download the theme from Themeforest.
Click the “download” button next to it and choose to download the “Installable WordPress Theme” which is just the WordPress file, or choose the “Main Files” which is the entire package that contains everything.
How To Update Your Theme Via FTP
Step 1 – Go to “wp-content -> themes” location and backup your “existing theme folder by saving it to your computer, or you can choose to simply delete it. Your content will not be lost.
Step 2 – Retrieve the extracted theme folder from the package you just downloaded from themeforest.
Step 3 – Then simply drag and drop the new theme folder into “wp-content -> themes” location. Choose to “Replace” the current one if you did not delete it.
How to update your theme through the Envato Toolkit Plugin
Please follow this guide here http://premium.wpmudev.org/blog/how-to-update-themeforest-themes-with-the-envato-wordpress-toolkit/
Will my modifications to theme be lost?
If you made modifications to the files of the theme, then yes. All your files edits will be lost. It is important that you backup your modifications so you can apply them back later.
Will my pages, posts or settings be lost?