Are you trying to monitor all of the instances, no matter what the instance name happens to be?
One thing you can do is monitor the Tomcat instance. When you add the counter and are given the thresholds to watch for, there is a little ... button at the right side of the counter path. Click that and you can directly edit the counter path. The counter path can have a * added to it, which will be expanded when the monitor runs. So you could change it to something like this:
\Prozess(Tomcat*)\Prozesskennung
\\Prozess(Tomcat*)\\Prozesskennung