Direto da documentação do Tomcat
Reload An Existing Application
http://localhost:8080/manager/reload?path=/examples
Signal an existing application to shut itself down and reload. This can be useful when you’ve recompiled classes on an application that is not configured with the reloadable=“true” attribute in its entry in $CATALINA_HOME/conf/server.xml, or when you’ve made other changes (such as to conf/web.xml) that are not automatically recognized by Tomcat.
If this command succeeds, you will see a response like this:
OK - Reloaded application at context path /examples
Otherwise, the response will start with FAIL and include an error message. Possible causes for problems include:
Encountered exception
An exception was encountered trying to restart the web application. Check the Tomcat 4 logs for the details.
Invalid context path was specified
The context path must start with a slash character, unless you are referencing the ROOT web application – in which case the context path must be a zero-length string.
No context exists for path /foo
There is no deployed application on the context path that you specified.
No context path was specified
The path parameter is required.