Just wrap in a queue where you can add more things to the front. It does mean you will have to split some things into two parts, but still is just a fairly simple change.

#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11144894
use warnings;

my @functionqueue = @ARGV ? @ARGV : qw( test1 test2 test1 ); # FIXME

while( @functionqueue )
  {
  for ( shift @functionqueue ) {
    /test1/ && do {
        print "test1 stuff\n";
    };
    /test2/ && do {
        print "test2 stuff\n";
        unshift @functionqueue, qw( test1 secondpartof2 );
    };
    /secondpartof2/ && do {
        print "secondpartof2 stuff\n";
    };
    }
  }
[download]

Outputs:

test1 stuff
test2 stuff
test1 stuff
secondpartof2 stuff
test1 stuff
[download]