Note that a block by itself is semantically
    identical to a loop that executes once.  Thus
    `last' can be used to effect an early exit out of
    such a block.
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An "if block" is not considered a looping construct on it's own, it's an exception, so the loop exit statements don't work. What you can do is make the "if block" contain just a "bare block". Since a bare block is considered a loop then it works, so:

if (true) {
  yada;
  yada;
  next if $foo;
  yada;
  yada;
}
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Doesn't work,

if (true) {
  {
    yada;
    yada;
    next if $foo;
    yada;
    yada;
  }
  # next comes here
}
[download]

Does.

Nuance

Baldrick, you wouldn't see a subtle plan if it painted itself purple and danced naked on top of a harpsichord, singing "Subtle plans are here again!"

(I feel dirty even mentioning it)