If you need to make mass modifications to SharePoint list content it is always good to copy the data into Excel and do a find/replace and copy it back to the SharePoint list. If you do the same procedure with hyperlinks, you will find out that it always copies the old hyperlinks back into the list, no matter what you try. This is caused by Excel translating the column data automatically into hyperlinks – a search/replace simply won’t change the underlying hyperlink.
Right-click every cell and select “remove Hyperlink” in the drop-down menu. This translates the cell content into “text” and then it can be copied and pasted back to the SharePoint list including the modifications.