Assuming the keyword might appear in more than one column and anywhere in the row try this

#!/usr/bin/perl
use strict;
use Spreadsheet::ParseExcel;
use Spreadsheet::WriteExcel;

my $KEYWORD = 'output';
my $parser   = Spreadsheet::ParseExcel->new();
my $workbook = $parser->parse('formatting.xls');

if ( !defined $workbook ) {
    die $parser->error(), ".\n";
}
my $workbook1 = Spreadsheet::WriteExcel->new("perl.xls");

foreach my $worksheet ( $workbook->worksheets() ) {
  my $name = $worksheet->get_name();

  # create worksheet with same name
  my $worksheet1  = $workbook1->addworksheet($name);
  
  my ( $row_min, $row_max ) = $worksheet->row_range();
  my ( $col_min, $col_max ) = $worksheet->col_range();
  next unless ($row_max >= 0 && $col_max >= 0); # skip blank sheets

  print "
  PARSING WORKSHEET: $name   
  ROW_MIN = $row_min, ROW_MAX = $row_max;
  COL_MIN = $col_min, COL_MAX = $col_max
";
  
  my $copyflag;
  my $col1 = 0;
  for my $col ( $col_min .. $col_max ) {
    $copyflag = 1;
    my @rowval = ();
    for my $row ( $row_min .. $row_max ) {
      my $cell = $worksheet->get_cell( $row, $col );
      next unless defined $cell;
      my $val = $cell->value();     
      print "Col, Row, Value = ($col, $row, $val)\n";
      $rowval[$row - $row_min] = $val;
      if ($val =~ /$KEYWORD/i){
        print "$KEYWORD found in column $col\n";
        $copyflag = 0;
      }
    }    
    
    # copy to new sheet
    next if ($copyflag == 0);
    for my $row1 (0..$#rowval){
      $worksheet1->write($row1, $col1, $rowval[$row1]); 
    }
    ++$col1;
  }
}
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