Find and Replace strings with the palette UI of Autodesk® AutoCAD®. Also, it is possible to use regular expression searching, to make it easier to search and replace your necessary characters.
You can try Express String Find/Replace for 15 days without any limit.
If you want to buy this application, start the 'DF_REG' command and follow the purchase procedure.
To start with the economical option, the license is available at 50USD (prepaid).