There are other ways, too...

#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11114679
use warnings;
use Data::Dump qw(pp dd);

my $A = [[1,2],[2,3]];

my $B = eval pp $A;

sub add1 { ref $_[0] ? [ map add1($_), @{$_[0]} ] : $_[0] + 1 }

my $incremented = add1( $A );

dd $A;
dd $B;
dd $incremented;
[download]

Outputs:

[[1, 2], [2, 3]]
[[1, 2], [2, 3]]
[[2, 3], [3, 4]]
[download]