I don't count 'user errors' as errors. So I wouldn't mess with die (I keep that for errors in the code).

What I often do in these cases is for the method/sub to return a hash.

(
  success => 0,
  data    => q{whatever},
  message => q{something horrible happened},
)
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my %result = validate($arg1, $arg2);
if ($result{success}){
 # woot! we can continue
 # do something with $result{data}
}
else{
 # try again
 send_screen_back($result{message});
}
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