A quick google search shows that you need to increase the Cache-limit
in /etc/apt/apt.conf. I just had to increase mine a couple days ago.
Here's my apt.conf:
bs:~$ cat /etc/apt/apt.conf
APT
{
Default-Release "stable";
Cache-Limit "14194304";
};
DSelect
{
Clean "prompt"; // always|auto|prompt|never
};
Brian