[ferget]

можно например так

Код:

Set infile=1.txt 
Set find=Иванов Иван
Set replace=Петров Петр

setlocal enabledelayedexpansion 
for /F "tokens=* delims=," %%n in (!infile!) do ( 
set LINE=%%n 
set LINE=!LINE:%find%=%replace%! 
@echo !LINE!>>2.txt
)
endlocal
del 1.txt
ren  2.txt 1.txt