One solution is to make an Editor Utility Widget to help.
Create one Editor Utility Widget (In the Asset Browser’s Add menu, it has an Editor Utility group), you can add a button and bind your Replace function to it.
Editor Utility class has the built-in node to get all actors of a certain class. So we can add all of Static Mesh actors into an array, then loop through them to decide (use some rules like name prefix) if each should be replaced with another actor, and then move it into a new desired folder if needed.
PS: right-click the Editor Utility Widget to Run it