Wait...you're going to kill her because she doesn't lay. IMO, that's absolutely not an option. Give her to someone as a pet, don't kill her because she hasn't breed for two years.
Other than that, there are plenty of people that have waited 2-3 years for a female to finally lay. It just depends on how long you are willing to wait. I can understand not wanting to keep a female around that hasn't bred, but not culling her.
LOL, I doubt Serpent is meaning to kill, yes cull generally means that but I think they mean to remove from the breeding program, not literally kill the snake