use strict;
use warnings;

my $i = 1;
while (<DATA>) {
    if (s/(LKTA_mic)\d/$1$i/) {
        $i = ($i == 4) ? 1 : $i + 1;
    }
    print;
}

__DATA__
Name - John
filename "LKTA_mic4.cfg"; }
Name - Tim
filename "LKTA_mic2.cfg"; }
Name - Jane
filename "LKTA_mic1.cfg"; }
Name - Jim
filename "LKTA_mic3.cfg"; }
Name - Don
filename "LKTA_mic1.cfg"; }
Name - Cody
filename "LKTA_mic4.cfg"; }