You probably want something like the following (untested) code:

#!/usr/bin/perl
use strict;
use warnings;
use Net::Appliance::Session;

my @ipconadd = qw(1.1.1.1 2.2.2.2 3.3.3.3);

doStuff($_) for @ipconadd;


sub doStuff {
    my ($host) = @_;

    eval {
        my $session = Net::Appliance::Session->new(
            {
                personality => 'ios',
                transport   => 'SSH',
                host        => $host
            }
        );
        
        $session->connect({username => 'admin', password => 'coolbro'}
+);
        $session->begin_privileged({password => 'verycoolbro'});
        print $session->cmd('show hostname');
        print $session->cmd('show inventory | i SN');
        $session->end_privileged;
        $session->close();
        return 1;
    } or do {
        my $err = $@;
        warn "Failed to doStuff for '$host': $@\n";
    };
}
[download]

Note the for loop over hosts that calls the sub to do stuff. The loop could be written long hand as:

for my $host (@ipconadd) {
    doStuff($host);
}
[download]