Kribs are kinda funny. You dont really breed kribs... they breed themselves. They will pick a compatible mate. They will make a breeding spot. They will decide when to breed. They will raise the babies.
Have you done anything different lately to the tank? If not then i would just wait and they will soon try again. I find mine breed every 6 weeks or so if i remove the babies. If the babies are still there.... they will hold off on making more.