Hi,
Check out Adam's stubborn breeder tricks page.
How are the snakes eating?
Is the male losing condition or have problems around his vent?
Since two of my girls didn't lay at all last year my male has been getting periodic (but widely spaced ) conjugal visits for over a year.
But if he stopped eating or developed other problems then I would definately stop pairing them up till he was back in form.
Hopefully some of the more experienced members can give you more specific advice though.
dr del