SEPM content folder disk usage really big

OS: windows server 2012

Version: SEPM 12.1.1989.1989

I tried the solution was given in this discussion http://www.symantec.com/connect/forums/sepmanager-121-and-huge-inetpubcontent-folder

but when I start the service again, the scm.lucontentcleanup.threshold=5 in the conf.properties would be gone and after the deleting the subfolders in the content folder it would return and eat up the disk space.

Can anybody help me? Thanks.