亡羊补牢 (wáng yáng bǔ láo): lit. to mend the pen after sheep are lost; fig. to act belatedly; better late than never

亡wáng羊yáng补bǔ牢láo

lit. to mend the pen after sheep are lost; fig. to act belatedly; better late than never

Fix the pen after losing sheep. Unlike the English sense of shutting the stable door, this one is encouraging: still worth doing.