$text =~ s/%/%%/g;
    # replace first block with "(%1%)"
    # replace second block with "(%2%)"
    # ...
    my %subs= (
        replaceThis => "withThis",
        # ...
    );
    for(  @subs{ keys %subs }  ) {
        s/%/%%/g;
    }
    $text =~ s/$_/$subs{$_}/g
        for keys %subs;
    # replace (%1%) with original first block
    # ...
    $text =~ s/%%/%/g;