Hey all, I got a 3GS, 4.0(8A293), 5.13.04, MB715LL. I first jb with jailbreakme.com and ultrasnow. A lot of the apps in cydia are not working and I’m getting an error going into cydia.

My question is if I update to 4.2 will I loose my jb?? What should I do, should I upgrade or what?? Please help.