Well I played with your code, and what I think you need to do is reset the canvas size and scrollregion when you call the sub. The way your current code works, you make the fractal bigger, but never adjust the canvas size to accomodate it. This is as far as I got, before the cpu usage made me give it up. I added scrollregions, adjust $c_size with $scale, and set the $scale to 1.2 to troubleshoot easier. Anyways, click this a few times and watch what happens, compared to your original script.

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

my $c_size = 100;
my $scale = 1;

my $mw = MainWindow -> new;
my $canvas = $mw -> Scrolled('Canvas',
         -height=>$c_size, 
     -width=>$c_size,
     -scrollregion => [0,0,$c_size,$c_size]
     )-> pack(-expand=>1 ,-fill=>'both');
     
$canvas -> Tk::bind('all', '<ButtonPress-1>' => \&MakeMan);
&MakeMan();

MainLoop;

sub MakeMan(){
  my ($e, $canv_x, $canv_y)=(0,$c_size/2,$c_size/2);
  if($scale > 1){
    $e = $canvas -> XEvent;
    $canv_x = $e->x;
    $canv_y = $e->y;
  }

  my $icount = 1;
  
  $c_size *= $scale;
  
#problem here...
  my $i = -2/$scale + (($canv_y-($c_size/2)) / ($c_size/$scale));# + $
+lasti;
  my $rgb;
  while($icount <= $c_size){
#... and here...
    my $r = -2/$scale + (($canv_x-($c_size/2)) / ($c_size/$scale));# +
+ $lastr;
    my $rcount = 1;
    while($rcount <= $c_size){
      my $tr = $r;
      my $ti = $i;
      $rgb = '#000000';
      for my $n(1..15){
        ($tr, $ti) = (($tr ** 2) - ($ti ** 2) + ($r), (2 * $tr * $ti) 
++ ($i));
        if((($tr * $tr) + ($ti * $ti)) > 4){
          $rgb = '#ffffff';
          last;
        }
      }
      $canvas -> createLine($rcount, $icount, $rcount+1, $icount, -fil
+l => $rgb, -width => 1);
      $rcount ++;
      $r += (4/$scale)/$c_size;
    }
    $icount ++;
    $i += (4/$scale)/$c_size;
  }
  $scale = $scale * 1.2;

$canvas->configure(-scrollregion=>[0,0,$c_size,$c_size]);
$canvas->update;

}
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