...

# global variables
my $col_0;
my $col_1;
my $col_2;
my $col_3;

...

for ( my $row=0; $row<2; $row++ ) {
        for( my $col=0;$col<$#headers+1;$col++) {
                my $e;
                if( $row == 0 ) {
                        $e = $tableWidget->Button ( 
                                -relief         => "groove", 
                                -justify        => "left", 
                                -text           => $headers[$col], 
                                -state          => 'active',
                                -width => length($headers[$col])
                                ); 
                } else {
                        if      ( $col == 0 ) { 
                                $e = $tableWidget->Entry ( 
                                        -width => $lens[$col], 
                                        -textvariable => \$col_0);
                        } elsif ( $col == 1 ) {
                                $e = $tableWidget->Entry ( 
                                        -width => $lens[$col], 
                                        -textvariable => \$col_1);
                        } elsif ( $col == 2 ) {
                                $e = $tableWidget->Entry ( 
                                        -width => $lens[$col], 
                                        -textvariable => \$col_2);
                        } elsif ( $col == 3 ) {
                                $e = $tableWidget->Entry ( 
                                        -width => $lens[$col], 
                                        -textvariable => \$col_3);
                        } 
                        $tableWidget->put( $row, $col, $e );
                }
        }
}

...

sub update {
        ...
        @data = ( / ... big long regex ... /g);
        ...
        $col_0 = data[0];
        $col_1 = data[1];
        $col_2 = data[2];
        $col_3 = data[3];
}