I relapsed the second I stopped taking accutane myself. But chose not to take a second round because accutane is so hardcore and changes your entire body forever.
So, that would be the first thing I'd say is are you absolutely sure it's worth it to take it a second time?
If you're 100% sure you've considered the rest of your life and decided it's worth it, here's some info on relapse. I am currently researching the last 2 years to update this article amongst others, so I don't have the last 2 years of data for you, but this is what I have so far.