You can automate via ftp. Give google a url to download and they will pull it from your site as often as you want. Also, in case you didn't get their announcement, they are killing the free listings. You need to have an adwords ppc account and use the product listings. http://support.google.com/merchants/bin/answer.py?hl=en&answer=2634840
WTF.. Killing free listings is going to make Google Shopping/Products totally useless.. Looks like I have to find a better place to compare prices lol.