Extend loadUI 2.0 JVM settings on Windows Controller

I'm running on a Windows controller with 4GB of memory. I have 35-minute runs of my test (to go through cache resets several times) and have a LOT of data to collect and report on. There are times when the report just DOESN'T generate. I suspect that the JVM is at its memory limit and cannot render the report. (though it seems to try but come back with no report - as though I hadn't selected the report icon [and OK button] at all)

I've tried to change the values in the sjvm and .bat files - but that just causes an error. Please help with specific steps to increase the JVM settings SAFELY on a Windows controller. (could it be about re-saving as a certain file type? Encoding? I give up)

Thanks.