This uses a helper batch file called repl.bat
from - https://www.dropbox.com/s/qidqwztmetbvklt/repl.bat
Place repl.bat
in the same folder as the batch file or in a folder that is on the path.
It should be more robust and faster.
type file.csv |repl "NULL" "-1" |repl "N\.A\." "-2" >newfile.csv