And one might add that the cells themselves are hardly immune from "renewal" at the molecular level. So the short version is: If identity requires complete coincidence of matter, then essentially nothing but sub-atomic particles survive over any reasonable stretch of time. That does rather suggest, though the contrary view is certainly held, that identity over time simply does not require complete coincidence of matter. What it does require is not very clear, but that is no reason to despair.
Of course, the question didn't ask about complete coincidence of matter. But it's unclear why anything less might suffice. And, if it does, then you run into issues about transitivity: A might share much of its matter with B, which shares much of its matter with C; but A and C do not share much of their matter.