I lost mine the first time after having my membranes stripped at 39 weeks. I lost it the second time the day I delivered. I don't think mine regenerated as much as it was just 'what was left' on my delivery day. The only difference that day was that I also had more blood.
Re: If you lost your mucus plug
#1 -> 3 1/2 days later
#2 -> didn't notice it (somehow?)
5 weeks.
1 1/2 weeks later when i was induced.