Giving dawah to someone with kufr beliefs

When the case of truth has been presented in an effective and wise manner (for example the absurdity of the Trinity to a Catholic or an exposure of who Mirza Ghulam Ahmed really was to a Qadiani), if the non-Muslim chooses to remain firm on their kufr beliefs, should we stop giving them dawah or should we be persistent in Dawah to those kuffar who are arrogantly stubborn in their beliefs?