We have the same issue in our environment that we've solved by placing the script on the desktop for users to reconnect the drives themselves. Our current version Cisco vpn allows for preauthentication so that Windows connects after the vpn and maps normally.
That being said, a startup script won't work because the machine has already been started when the connection is made. The suggested task with a date in the past would run once but not reoccur.
Does your checkpoint or client offer any ability to run a script upon connection?