Did you try it? next doesn't apply to if-blocks, it applies to the enclosing loop-block (for or while, or a naked block which is a loop executed once) ... if-blocks are not loops. Similarly for redo and last.

And if you do have nested loops, you can always break out of the one that you want by using labels...

LAB_1:
  while ([cond1]) {

LAB_2:
    while ([cond2]) {
      next LAB_1 if [cond3];
    }
  }

As archon says, its all there in the perlsyn page.