Roof repair means fixing the specific fault rather than replacing the whole roof. That could be a slipped or cracked tile, failed flashing around a chimney, a split in a flat roof, a blocked or broken gutter causing water to back up, or damage after a storm. The important part is finding what's actually causing the problem. Water travels, so the stain on your ceiling is often nowhere near the hole in the roof, which is why patching the obvious spot frequently doesn't work.