The earthly copies required these rituals to be purified. But the heavenly things themselves required better sacrifices. Christ didn't enter a sanctuary made by human hands — those were only copies of the real thing. He entered Heaven itself, to stand in the presence of God on our behalf.
And he didn't go there to offer himself over and over, the way the High Priest enters the holy places every year with blood that isn't his own. If that were the case, he would have had to suffer again and again since the beginning of the world. But instead, he appeared once — at the climax of history — to put away Sin by the Sacrifice of himself.
Every person is appointed to die once, and after that comes Judgment. In the same way, Christ was offered once to bear the sins of many. And he will appear a second time — not to deal with sin again, but to bring Salvation to those who are waiting for him.