I don't think this is possible...
basically because the Simulator use a lot of files (.log .dmp) during its execution, these files allow the simulator to save states and your last activity with it, so you can see this state on further executions...
One thing you can do is using ANT to automate some building task for you applications tests:
- delete old application files
- delete these dmp and log files (leaving just the .xml and .bat) USEFUL when you need to do a "hard reset" in the simulator
- to copy the necessary files in the simulator folder (.cod .debug etc)
you need to be sure of having the simulator closed before trying the second task, otherway the build will fail
at least with ANT tasks automatization you will only have to close and re-open the simulator to see your application last version.
check this link for ANT in BlackBerry
Dr. Dobb's | BlackBerry Development: Using Apache Ant | September 29, 2004
I hope this help
Regards