Don't know if you are a perl person......

But, one method is to create a bunch of create commands from your exported 
output list from nsradmin.  each client create command should look like this:

create  name: client1; scheduled backup: Enabled; comment: OSFullThur; 
schedule: Full Every Thursday; browse policy: 37Days; retention policy: 37Days; 
directive: Unix without dbf - Solaris 10; group: ISFarm_OS; save set: All; 
backup command: ; server network interface: ; aliases: client1, 
client1.xxxdev.com ; parallelism: 4; type: NSR client;

Once you have the list of create commands, they need to get fed into an 
nsradmin -i command.

Here's a perl program that creates the necessary input to an nsradmin -i 
command to create clients.

The output this creates will displayed on the screen.... you'll have to capture 
that output via a pipe or some other method (like updating the program to write 
to a file) so it can be used as input to the nsradmin -i command.

Also, the first line: @nsrclients creates my equivalent to your exported list.  
You can change it read your already existing list like this:
@nsrclients=`cat yourlist_location`;

Don't know if any of this helps you..... It's the method I used recently to 
re-create a bunch of clients on a new server.....


#!/usr/bin/perl
#
#  script to create an input file to be used to create Networker clients via 
the command line
#   via the nsradmin -i command
#
# first step is to create the list of fields you want to create the new clients 
from
@nsrclients=`nsradmin -i /export/home/japgar/nsradmin_list_create_clients.txt`;
chomp @nsrclients;

$jstr="";
$first=1;

foreach (@nsrclients)
{
  $_ =~ s/^\s+//; # strip out leading whitspaces
  $_ =~ s/\s+$//; # strip out trailing whitspaces
  if( $_ =~ /name:/)
   {
     if($first eq 1)
       {
         $first=0;
         $jstr="$jstr $_";
         next;
       }
     print "create $jstr type: NSR client; \n\n";
     $jstr="";
   }
     $jstr="$jstr $_";
}
print "create $jstr type: NSR client; \n\n";

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