Can I resume retopologizing a mesh in Retopoflow after exiting the tool? I'm learning how to use Retopoflow 3.0.  I've found that after exiting the tool by pressing the tab key that there seems to be no way to activate the tool again and resume editing my retopology mesh from the point where I left off - so it looks like you have to do your retopology all in one shot.  This makes it hard to deal with sculpt errors that you don't notice until you're well into your retopologizing job.
Am I wrong?  Is there a way to continue from where you left off?
I ran into this problem as well. You have to be in edit mode to re-enter Retopoflow.
With the RetopoFlow mesh selected in edit mode, press the diamond button to start RetopoFlow or open the menu and pick any of the RF options.

So, thankfully there is no need to retopologize all in one go.