System-User not able to find System User

I have a Apache Sling service-user-mapping setup, mapped to a system user. I then create a system user. My Sling Servlet is working as expected, able to get content via ACL rules. A couple of days later, it the Sling Servlet returns an error in the log. The error says "service-user-mapping found, but system user cannot be found". I restarted AEM and it worked again... What OSGI component will I need to restart to refresh the system users entry? for me not to get the error of system user cannot be found?