A rebrand moves the site to a new domain. Every internal link reference, every redirect mapping and every tracked URL in the analytics configuration carries the old domain.
The mechanical part
Replace the old domain with the new one across the whole list. Three thousand rows update in one pass, consistently, which is the only way this gets done without introducing errors.
Build the redirect map from both versions
Keep the original list beside the rewritten one. Old and new side by side is the redirect map, and having it generated rather than typed removes the most common migration failure — a mapping that points somewhere subtly wrong.
Where paths changed too
A pure domain swap is the easy case. If the new site also restructured its paths, the replacement gets you the domain and the path mapping still needs doing per section. Do not let the ease of the first part disguise how much of the second remains.
Try it: Find and Replace Text on SeoWolf's Notepad.