Smells a wee bit like homework, but try:

LOOP: {
    $choice = <STDIN>;
    if ($choice == 1)
    {
        &hash1;
    }
    elsif ($choice == 2)
    {
        &hash2;
    }
    elsif ($choice == 3)
    {
        &hash3;
    }
    else
    {
        print "ERROR: Please type in either 1, 2 or 3.\n";
        redo LOOP;
    }
}
[download]