This will do the trick

$input = "
1234567890123456789012345678901234567890123456789012345678901234567890
+ 
1234567890123456789012345678901234567890123456789012345678901234567890
+ 
1234567890123456789012345678901234567890123456789012345678901234567890
+ 
1234567890123456789012345678901234567890123456789012345678901234567890
+ 
";

# do the magic with a snazzy regex

$input =~ s[(\S+)]          # grab the words into $1
{    
   local $_ = $1;           # assign word to $_
   if (length $1>30) {      # if word to long
       s/(.{30})/$1 /g;     # add spaces every 30 char
   }
   $_;                      # substitute in $_ for word
                            # it may or may not have changed
}gex;                       # global, execute, comments

print $input;
[download]

Note I have assumed that the words are any consecutive non whitespace chars

cheers

tachyon

s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print