If your site is suffering from a Penguin penalty, Google says you can only recover when it runs the algorithm again. In response to a question posted in the Webmaster Central Help Forum asking “Can a site really recover without Google doing another Penguin update? Is there a definitive answer?” Google’s John Mueller replied, “Yes, assuming the issues are resolved in the meantime, with an update of our algorithm or its data, it will no longer be affecting your site.”
Although the answer seems very obvious, this is something many people argue about. However, as Google says, the only way to recover from an algorithmic issue is for the algorithm to run again. With Penguin it has been more than 11 months since the last refresh was made.
So if your site has been hit by the Penguin 2.1 update, you are stuck until Google makes an algorithm update again. As of now, all you can do is stay patient and wait for the next Google Penguin update.