The answer to 'when to replace leak repair' is that leak repairs are generally a temporary fix and should be replaced with a more permanent roof repair or replacement when the leaks become frequent or the damage to the roof becomes extensive. Roof leaks that are repaired but continue to recur, or that lead to other issues like mold, rot, or structural damage, are signs that the roof needs to be replaced rather than just patched.
Roof leaks can be caused by a variety of issues, including worn shingles, cracked flashing, or damage to the roof deck. Temporary repairs like sealants or patches may work for a while, but they won't address the underlying problem. If you find yourself having to make repeated leak repairs, it's usually more cost-effective in the long run to replace the entire roof.