If you’re supporting an end user on Windows XP, Vista, 7, 8, or 10, and don’t want to completely log them out, you can use Run As on a Command Prompt as an administrator and then run the following:
rundll32 sysdm.cpl,EditEnvironmentVariables
Now edit your variables and relaunch your application. This is very useful if you find yourself needing to correct the PATH, let’s say, for Java.