In a Google Hangout, Google’s John Mueller said that you usually do not get your rankings back after a penalty:
“In general, we will try to take that into account. When we see that site make significant changes in the quality of the pages. So that’s something where I suspect you’ll see positive changes.
It’s almost never going to be that we will just restore the previous state because things evolve on the Internet, things evolve in our algorithms and any previous state will be different when we look at it now.
So even if nothing happened with your website with our algorithms in the meantime the rest of the web will have evolved, so that previous state might be different from the new state that that will come up.
That’s something where sometimes we see this question with regards to short-term changes that sometimes we also see this question with regards to long-term changes. Where it’s like ‘three years ago my site was ranking at this position for these queries and I fixed the issues that were involved, will my rank like that again?’ and obviously, especially over a longer period of time like a couple of years, that the web will have evolved, things will have changed quite a bit in search.”
You can see the video here: