This is the max, and yes, you can increase it. However, more than 200 is not supported, so you may run into problems, and TAC would require you to decrease the ceiling to 200 before troubleshooting.
If you're okay with that, you can modify the OGSClient.properties file under NMSROOT/MDC/tomcat/webapps/cwhp/WEB-INF/classes, and increase MaxLimitforGroups.