my $t1 = $top->Label(-text=>"$host",-background => "$color")->pack();
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Rather than repeatedly creating and pack-ing a new  Label widget into its parent as is now done, try re-configuring the options of an existing widget with  configure (see discussion of this method in Tk::options):
    $label_widget->configure(-text => $new_text, -background => $new_color);
(Again, this assumes the label widget has already been created and packed somewhere else in the code.)

BTW: It's not necessary to interpolate a scalar into a string (e.g.,  "$host" in the OPed code) in order to use it as a string.

Also BTW: I share your liking for Tk, all the more since I have some hard-won experience with it. But, sadly, it seems possible it may have become an orphan application. See various discussions on PerlMonks of Tk vis-a-vis Gtk2 and Wx.