Your code doesn't look like a real program to me but just as a bunch of editing commands to convert exactly one kind of input to exactly one kind of output. I don't know, whether or not my attempt fits your needs, but try for yourself... 
use strict;
use warnings; # use these two always!

my $pattern= qr/^(Line '(\d+)')$/; # This is the line you're searching
+ for
my @holdspace;

while (<DATA>) { #read the input
        if (my $hit= /$pattern/o .. not /$pattern/o) {
                # this will be executed for every Pattern-line
                # and the line after that. 
                if ($hit==1) {
                        # If it was the first: Clear the holdspace
                        @holdspace= ();
                }
                elsif ($hit=~ /e0/i) {
                        # If it's the last print everything
                        print "NewLine1\n",@holdspace,$_;
                        next;
                }
                # Store the pattern lines
                push @holdspace, "(+$2) $1;fac=$2\n";
                next;
        }
        # Print everything else
        print;
}
# That's it
print "MeanLine\n";
__END__
Line1
Line2
Line3
Line '1'
Line '2'
Line '3'
Line4
Line5

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In reply to Re: sed to perl conversion revisted by Skeeve
in thread sed to perl conversion revisted by NovMonk

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