Have you looked at the FAQ, How do I reformat a paragraph? The core module Text::Wrap may be all you need:

use strict;
use warnings;
use Text::Wrap qw($columns wrap);

$columns = 80;
print wrap('', '', <DATA>);

__DATA__
The quick brown fox jumped over the lazy dog. The quick brown fox jump
+ed over the lazy dog. The quick brown fox jumped over the lazy dog. T
+he quick brown fox jumped over the lazy dog. The quick brown fox jump
+ed over the lazy dog. The quick brown fox jumped over the lazy dog. T
+he quick brown fox jumped over the lazy dog. The quick brown fox jump
+ed over the lazy dog. The quick brown fox jumped over the lazy dog. T
+he quick brown fox jumped over the lazy dog. The quick brown fox jump
+ed over the lazy dog.
[download]

Output:

 2:13 >perl 935_SoPW.pl
The quick brown fox jumped over the lazy dog. The quick brown fox jump
+ed over
the lazy dog. The quick brown fox jumped over the lazy dog. The quick 
+brown fox
jumped over the lazy dog. The quick brown fox jumped over the lazy dog
+. The
quick brown fox jumped over the lazy dog. The quick brown fox jumped o
+ver the
lazy dog. The quick brown fox jumped over the lazy dog. The quick brow
+n fox
jumped over the lazy dog. The quick brown fox jumped over the lazy dog
+. The
quick brown fox jumped over the lazy dog.

 2:13 >
[download]

Hope that helps,