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. Perhaps you mean you are going to give/sell her to someone else? When I think of culling a BP, to me that means they are going in the freezer.