This is not very well tested, but how about:
use re 'eval';
my $str = "111111111";
my $times = 5;
my $re = qr/1/;
my $cnt;
$str =~ s/$re(?(?{++$cnt > $times})\A)/2/g;
print "$str\n";

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Turning this into a subroutine is left as an exercise.

In reply to Re: Substitute (s///) a set of times by runrig
in thread Substitute (s///) a set of times by jryan

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