I have changed computer/IP address of my ADNM server. My computers running avast from the old mirror will not update now that the old ADNM server is gone. I would think that the new ADNM server would reinstall avast on the computers but it won’t. What are my options? Is there a way on the pc to point it to the new ADNM Server?
Open the ADNM console, right-click the “Computer Catalog” and click properties.
Click the “Communication” tab, and input the correct AMS address.
The IP for the new adnmis right but 25% of my computers are still looking for the old server. I was wondering how I can get the computers pointing to the old server to point to the new server.
RTFM… (the best way is RTFM before doing change)
See CHAMS tool in manual…
Other possible way I suppose - try change IP on new AMS server for a short time, wait when this “25%” your PC’s start communicate and download new configuration (while that time other 75% will not see your new AMS server), and after it, change IP back… Maybe is it better, than running CHAMS tool on every “25%” computers… 
Yes, RTFM is a good idea.
Accessible from here:
http://www.avast.com/community-and-support
http://download850.avast.com/files/eng/adnmag.pdf
open a command prompt on a client
go to the directory where you installed avast and run the command:
aswchams xxx.xxx.xxx.xxx
where xxx.xxx.xxx.xxx is the IP address of the new AMS server.
unfortunately you need to do this on all the stations individually
not if they use the script idea from this post…
i was giving the TS some material to find out on his own how to make live easy 
but yes you can use that script