Hi
I had this problem (runny camembert).
My problem was not over ripening. The cheese would be runny near the rind even before the ripening
process reached the center of the cheese.
I solved it (I think) by adding 1/2 hour of acidification before renneting (as suggested by Nabil), and upping
the temperature to 90F (84F was my original temp, from recipe in The Cheesemakers Manual by Morris).
This results in more liquid being expelled from the cheese.
The resulting cheese had a consistency more like commercial camembert, even after 6 weeks in the cave.
So I encourage you to experiment with raising the renneting temp a little or lowering the pH as little (by increasing
acidification time).
-Carl