Assuming your text file is DataCollected.csv and assuming it resides adjacent to the batch file, some clues [untested]:
findstr /r "^%ComputerName%," "%~dp0DataCollected.csv" || for /f "delims=" %%a in ('cscript "C:\Program Files\Microsoft Office\Office15\OSPP.VBS" /dstatus') do echo %computername%,%%a>> "%~dp0DataCollected.csv"