How can i update my theme safely?

Go to your themeforest account and in download page, re-download the theme (updates are free).
Then go to your admin page > appearance > themes , deactivate and remove current theme and re-upload new version.

Note: You are just replacing theme files, so your setting, customization and contents are safe in database, but also you can backup your website using WP DB-Manager for sure

After updating your theme, please hit “Save all options” button in Option panel. because theme needs to re-cache options after each update.
(screencast is also available)

 

More articles to read :

– I cant upload my wordpress theme in admin area

– How can i upload my theme using FTP?