repeats=2
while read line; do yes $line|head --lines=$repeats; done < infile > o
+utfile
[download]

This is not Perl code. It looks like some kind of shell script.

Here's another approach to the problem that uses a script rather than a one-liner. I'm assuming you know how to handle file input/output, so this is just an example of a regex. This code needs Perl version 5.10 or greater; if you have an earlier version of Perl, a fix can be supplied.

Win8 Strawberry 5.30.3.1 (64)  Sun 05/23/2021  2:40:51
C:\@Work\Perl\monks
>perl

use 5.010;  # need regex extended pattern \K

use strict;
use warnings;
use autodie;

my $data = <<'EOD';
module abc(

rist_top_tck,

rist_top_tdi,

rist_top_tdo,
EOD

open my $fh, '<', \$data;

while (my $line = <$fh>) {
    $line =~ s{ \A (\w+) \K (?= ,) }{($1)}xms;
    print $line;
    }

close $fh;

^Z
module abc(

rist_top_tck(rist_top_tck),

rist_top_tdi(rist_top_tdi),

rist_top_tdo(rist_top_tdo),
[download]