Hello Kundan,
what do you mean by "replace the old template"? Do you just want to replace an excel-file in the KM? If yes, you can do that by opening the details of the file in the KM and in the Actions-menu you'll find the upload-option. By that you can just replace the content and the name etc in the KM stays the same.
If you meant something else, you need to explain more. 
Regards,
Steffi.
