Who says they need to be periodically reset? I have a router that is handling an ATM WAN, two PRI voice trunks for inbound and outbound calling, routing between multiple subnets at the site, and as a backup call controller for the phone system that has been up for over a year without any degradation in performance:
Houston3660 uptime is 1 year, 7 weeks, 4 days, 13 hours, 57 minutes
I have no intention of rebooting it unless I need to do a software upgrade or something else.