What you want is to have only one place where input is accepted and then many checks that all return to that one place if they find fault:

while(1) {
  $date = <>;
  ...
  if (...) { print "was wrong"; next; }
  if (...) { print "was very wrong"; next; }
  if (...) { print "totally wrong"; next; }
  last;
}
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Now almuts suggestion is a step further than this. She suggests putting this into a subroutine and use 'return($date)' instead of the 'last'. That would do exactly the same but would be even more readable