This simple WordPress plugin created by Måns Jonasson is useful for almost anyone who maintains a WordPress site of any size, but it’s especially useful if you maintain documentation of any kind and have a frequent need to update screenshots. It does exactly what the name implies — it makes it easy for you to replace one image file (or any other type of file) with another. No more uploading a new file and deleting the old one, or confusion over versions or file names.
Once you install and activate this plugin, you’ll find a new button labelled Replace Media at the bottom of the Edit Media page. Click this and browse and select a file from your computer. You then have two choices — you can either retain the original file name (renaming the file you’re uploading if necessary) or you can replace the file and use the new file name, changing all existing links to the old file to point to the new one. For the first option, you need to be uploading a file of the same type, but for the second option you can replace your original file with one of a different file type, like a gif with a jpg or a Word document with a PDF. Nothing fancy, but a great timesaver!
Enable Media Replace — Read more or download this popular plugin here