Yes, redo is good for that, but the if{}else{} control is less good. How about factoring the message out of an input sub?

sub get_input {
    {
        print @_;
        my $input = <STDIN>;
        chomp $input;
        redo unless $input;
        $input;
    }
}

my $PartNumber = get_input
        'What is the Part Number that you would like to look up?',
        $/;

my $Revision   = get_input
        'What is the Revision level for ',
        $PartNumber,
        '?',
        $/;
# go on to verify that those make sense, redo if they don't
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After Compline,
Zaxo