VPN connection in OSX fails after a certain amount of reconnects
This is actually a bug in Mac OS X, all Cisco IPSec connections have a timeout (hard limit of the lifetime) of 3600 second (60 minutes) because of the soft and hard limit of IPSec connections it is most of the time around 45 to 50 minutes.

You can check the files (with an active IPSec connection) in 

/var/run/racoon/


for the limits. On a Terminal type

sudo more /var/run/racoon/*.conf


and you can see the content of the config file for the active IPSec connection, all lifetime values are 3600 seconds

lifetime time 3600 sec


The bug exists since a long time and is still present for example in Mac OS X Mavericks (10.9.1). There is a workaround (more or less) for this check

Workaround

or

Apple Diskussion #2163407

or

Apple Diskussion #2743319

For Witopia it is easier to use the Mac OS X Client from Witopia

Witopia Client