how to adjust the number of DHCP require packets

[cute walker <cute walker gmail com>]

Hello.
I have a problem and need your help .
On my laptop it runs 
Ubuntu 10.04 , gnome 2.30.2 and NM 0.8 . I have enjoying them for more 
than one year. But nowadays I have a problem.
My laptop can not 
access the campus' wifi network for most time I try. After communication
 with the network administrator, we find the problem happens in the 
process of IP obtainment via DHCP. By capturing packets using wireshark,
 we find that the DHCP server is slow and my laptop  need 4 or more DHCP require packets before it can get a DHCP offer packet. But, after 3 DHCP require packets, my laptop will stop trying and deassociates the link on layer 2( IEEE802.11) . 

Of
 course, the network administrator has his work to speed up the DHCP 
server. But before he does, I still can not access the network.

Now my idea is to adjust the number of DHCP require packets
 while tring to access, namely, setting it bigger enough to get the DHCP
 offer packet. ( In fact , we find the Windows keep sending DHCP require
 packets  for many times, so Windows do not suffer this problem ). But I
 don't know how to do that.

So, can anyone of you give me a simple way to adjust the parameter?

Thanks!

your best , cute_walker.