Currently automatic updation feature is not available .
I use this handy plugin for auto updates of all plugins and themes –
http://wordpress.org/plugins/easy-theme-and-plugin-upgrades/
It makes a backup of the existing plugin/theme as well in the media folder so you can always revert back or refer to the earlier version. If you made any changes to the source files (instead of child theme), you will need to redo them of course no matter what method you use for updating.
Hope this helps.