If you’ve received an Update notification and you want to update the plugin on the last version first you need to download the latest uploaded file from your CodeCanyon account:
Go to: http://codecanyon.net/downloads
The safest way to update the Plugin to a new version is via FTP Upload. Just download the last version, unzip the file and copy the folder into your website on wp-content/plugins/ overwriting the current plugin folder.
Important: Important features and fixes are release into each update. If your plugin version is very old, to avoid undesired situations, keep a back-up of your current version before is overwritten with the last plugin version.