How to restart Command Prompt from Command Prompt

I am trying to set up a remote build server for Continuous Integration with Visual Studio Online. I run an npm install to set up the environment, in my case, to install the tns tools, so I can then run tns build, but I get an error saying tns isn't a recognized command. I believe I need to restart Command Prompt to get it to recognize newly installed commands.

How do I do this from the command line?

I tried this:

taskkill /IM cmd.exe

but I get an error saying The system caot find the path specified.

Here is the full output:

******************************************************************************
Starting task: Run TASKKILL /F /IM CMD.EXE /T
******************************************************************************
File name doesn't indicate a full path to a executable file.
Executing the following command-line. (workingFolder = C:a1s)
"TASKKILL /F /IM CMD.EXE /T" 
Error message highlight patte: 
Waing message highlight patte: 
The system caot find the path specified.
******************************************************************************
Finishing task: CmdLine
******************************************************************************
Task CmdLine failed. This caused the job to fail. Look at the logs for the task for more details.