When connection to Internet fails...

[Afsheen Ghorashy]

I have a laptop running Ubuntu.  Sometimes, during long sessions, my 
computer automatically releases the wireless connection.  When I try to 
connect again, it is not able to. 

My current solution is to restart the computer or to do sudo 
/etc/init.d/gdm restart. 

Is there any other service that I can restart that will just restart the 
internet connection interface (my goal is fix the problem without losing 
my session when this happens)?

Thanks,
Grasswistle