Happened to me too, it was my first autoblog actually. The traffic made me happy for a couple of weeks, then it drops to almost zero. The website disappeared from Google, so I gave up on the autoblog.
Then i don't know how many weeks later, the traffic was coming in again. I didn't do a thing, but the autoblog kept doing its thing. So my guess is to just keep posting and marketing your website, if the website get's old enough and has sufficient backlinks, then it will pop into google again