Clearing conntrack? Extending size of conntrack?

[James Strickland <jstic04@xxxxxxxxxxxxxxxxxxxxxxx>]

Hello, usually after about a day up uptime on my router, the ppp 
connection to my isp stays alive, but packets are not forwarded and 
nated through wan/lan interfaces.  My guess is that the conntrack is 
getting too large over this time (my brothers node uses nonsense like 
kazaa and bear share).  Is there a way to increase the conntrack size, 
or to clear it via /proc?

thanks.