To update to the latest version of the theme you have a few options.
NOTE: Before updating the theme we strongly recommend you backup
your live theme instance first! We also highly recommend you first
conduct updates on a staging/development version of your site to ensure
you conduct a full test of major theme and plugin updates in a safe
environment before going through the same process on your live site.
(Good WordPress hosts like Siteground offer the option of testing theme
and plugin updates in a safe staging environment) - http://www.commercegurus.com/siteground
We also assume in this update process that you have made no changes to the theme files yourself. If you have you will first need to move those changes to a child theme. We include a starter child theme in the main zip package which can be downloaded from themeforest. You can read more about child themes here:
http://www.commercegurus.com/2014/09/26/starter-child-theme-captiva-released/
http://codex.wordpress.org/Child_Themes
1.) Use the Envato WordPress Toolkit
http://www.commercegurus.com/2014/09/22/keep-captiva-date-envato-toolkit/
2.) Use the Easy Themes and Plugins upgrade plugin
https://wordpress.org/plugins/easy-theme-and-plugin-upgrades/
3.) Manually via ftp
- download the existing version of your theme in /wp-content/themes/
- put it in a safe backup location
- delete the live version of the theme
- re-upload the latest version