You do know that the second (else) substitution will never happen, don't you? The result of $table->cell($rownum, 0..2) does not have \xa0 in it (it didn't match the first match). So, you can simplify your code and write

$table->cell($rownum, 0..2) =~ s/\xa0\d+/ /;
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(hoping your method ->cell() returns a lvalue, of course)
Update: after looking at your code and TableExtract docs, I think what you want is something like:

foreach my $rownum (0..$#totalrows) {
  s/\xa0\d+/ /, push @title, $_ for $table->cell($rownum, 0) || '';
  s/\xa0\d+/ /, push @teach, $_ for $table->cell($rownum, 1) || '';
  s/\xa0\d+/ /, push @aides, $_ for $table->cell($rownum, 2) || ''
}
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