What you want to do is create your labels only 1 time, starting with an empty string of spaces as text. Then in your update sub, fill them in with a configure.

#!/usr/bin/perl
use strict;
use warnings;
use Tk;

my @array = ('red','green','yellow');
my @host_array = qw(server1 server2 server3 server4);

my %labs;

my $window = MainWindow->new();
$window->minsize( qw(250 250));
$window->title("Server Status");
$window->configure (-background => 'grey');

my $top = $window->Frame(-background => 'grey',)->pack(-side=>'top',-f
+ill=>'x');

foreach my $host (@host_array){
  
   $labs{$host} = $top->Label(-text=>"$host",-background => 'white')->
+pack();

  }


#$window->Button(-text => "Refresh", -command => \&pinghost )->pack;

my $timer = $window->repeat(2000,\&pinghost);

$window->Button(-text => "Quit", -command => \&Quit )->pack;

#&pinghost;

MainLoop();

#########################################################

sub pinghost{
  
   foreach my $host (@host_array) {
  
    push (@array,shift(@array));
  
    my $color = $array[0];
    my $rand = rand 1;
    
    $labs{$host}->configure(-text=>"$host-$rand", -background => "$col
+or");
  }
  #$window->update;
}

sub Quit{
  exit;
}
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