Sharepoint 2013 visual studio workflow is not updated on subsequesnt deployments

tasklist /FI "IMAGENAME eq vssphost5.exe" 2>NUL | find /I /N "vssphost5.exe">NUL
if "%ERRORLEVEL%"=="0" taskkill /f /im vssphost5.exe
exit 0

http://stackoverflow.com/questions/19286924/sharepoint-2013-visual-studio-workflow-not-updating