A person refuses to give up his kufr belief.

Answer

If he subscribes to a belief of confirmed unambiguous kufr and refuses to repent and renew his Imaan, then he will be out of the fold of Islam. There is no Janaazah Salaat for him nor should he be buried in a Muslim cemetery. It is essential for the Ulama at your end to explain to the person his folly and to try and convince him to renounce his baseless belief of kufr and repent.