You have two options using the Envato Market plugin to update all within the admin, quickly and easily. It comes packaged with WP Pro Real Estate 7 but for all my other themes you'll need to download and install it manually.
If you're running RE7 all you need to do is go into Appearance > Install Plugins > Install & Activate Envato Market, the old/outdate Envato Toolkit plugin will automatically be deactivated when you update the theme to 2.1.0+, once thats done just find the Envato Market nav item bottom left of your admin and follow the steps to get it setup.
Or via FTP to manually update the files outlined in the changelog, in case you've made local edits to the parent theme files.
- Download the latest version from your http://themeforest.net/downloads area
- Unzip the main download > unzip the theme file
- Connect to your server via FTP, I use filezilla-project.org for my client its a free download
- Upload the theme folder into wp-content > themes > overwriting your existing theme folder or upload individual files as outlined in the themes changelog (accessed from your theme admin options panel)
- That's all she wrote, enjoy!