The most involved relactation case that I followed was a baby who was breast fed for 2 months, then off the breast for 2 months.  From the first week of formula/bottles he had continuous ear infections and that was mom's motivation to try the relactation.  This little boy was very willing to go to breast feeding at 4 months, but I understand from the literature that many are reluctant after 3 months of age.  The baby I worked with was a large and vigorous boy.  His mother used an SNS for 7 weeks to get back a full milk supply.  He went on to nurse for 14 months.  During the period of relactation he was entirely free of ear infections.  He did have 2 more around his first birthday, but his health began to improve when his mom was only able to produce drops of milk. 
This case was very intense and there were many times that i was on the phone with this mom more than once a day.  There was at least weekly weight checks and a lot of communication with the pediatrician.  This mom needed everything i could give her in the way of support and she also used LLL peer support and read everything she or I could find.  It was inspiring to see her strength and resolve.  I found the LLL series helpful as well as the chapter in Riordan and Auerbach on Failure to Thrive  for use of SNS.  good luck. 
tracy throckmorton, rn ibclc  portland  oregon
tracy