It is better for Citrix to provide an update to avoid this problem.
I could give you directions to do some settings changes, but I'm uncertain whether or not they would impact the security. Make sure any that changing any of these settings in Apple's software won't do anything to compromise the security of your machine or the data being transmitted. They need to know when their certificates are going bad, because it could let a bad software leak through their download page and data transfer across the VPN could be insecurely transmitted.
