Whenever you update a plug-in in your WordPress blog, visit the plug-in settings page after you update the plug-in. Because there may be new options in the plug-in. If you don’t check the plug-ins setting page after you update, you will lose many new features of the plugin. So best thing is to go to the plug-in home page & check for the change-log of the plug-in & see what is new with the plug-in. So you can use all the new features of the plug-in.
Another case of this is some plug-ins reset their settings to Default settings after a new update. So if you had customized settings of the plugin (99% we do) you will lose the function of those settings. There are many plug-ins that we never go to the settings page once we have done the settings. So if the settings of it is set to default we never know it.
So once you have updated a WordPress plug-in, check both plugin home page & plugin settings page.