use strict;
use warnings;

my %MasterHash;
my $line = "k1:v1  k2:v2   k3:v3"; #the space is a tab

##some part of code that writes stuff to MasterHash
....

my @array1 = split (/\t/,$line);
my ( $index )= grep { $array1[$_] =~ /v3/ } 0..$#array1;
my $mv = splice @array1, $index,1;
print "after removing: $mv\n";
my ($mvl,$mvr) = split (/:/,$mv,2);
$MasterHash{$mvr} = map { split /:/; } @array1;

print Dumper \%MasterHash;

##</code><code>##

$Var1 = {
          'abc' => 'loaded before',
          'xyz' => 'loaded before',
          'v3'  => 16       #basically some number
        };

##</code><code>##

$Var1 = {
          'abc' => 'loaded before',
          'xyz' => 'loaded before',
          'v3'  => {
                     'k1' => 'v1',
                     'k2' => 'v2'
                   } 
        };