I just went through this too and was just about to fill out a "So What Happened" now that my baby is finally taking a bottle.
Here is my request and the advice that I received:
http://www.mamasource.com/request/13841482146180497409
Granted, my daughter wasn't given bottles on a regular basis, but she still took it when offered up until about 3 months as well. When I searched for advice online, I found that a lot of babies start to refuse at about this time. My own personal theory is that are becoming more aware at this stage and decide that they prefer mom's breast to the bottle. It was about that same time that my baby started to really cuddle with me, coo, and gaze at me during feeding time.
Anyway, we tried various bottles/nipples and techniques for over a month, but what finally worked for us was probably the most painful experience of my life. I had two days before I had to return to work and was growing desperate, so I finally began withholding the breast until she took the bottle. When she woke up in the morning, I gave her the breast for her first feeding and then each feeding after that offered the bottle. If she didn't take it, I didn't give in. I would just do my best to soothe her and calm her down. Typically, she'd cry for about 10 minutes and then fall asleep. Then I'd pump, and each time she awoke I offered the bottle again. Same story for about 7 hours. I continued to offer the same bottle each time (Adiri breastbottle), but finally around 7 hours if I even pulled out the bottle she'd lose it - so I reverted back to the Playtex drop-ins with the Natural Action Nipple (the nubby one) which she had taken before - and she took it without hesitation. From there, I continued to give her bottles with each feeding until the end of the day and then I nursed her for her last feeding. And ever since, she's taken a bottle from whomever (including myself) whenever offered but has no problem switching between breast and bottle. I work 3 days a week and she takes bottles when I'm away and breast when I'm at home.
Now, I would suggest this only as a last resort because not only is it difficult for baby, it is heart-wrenching for mother. I shed lots of tears and said lots of prayers. But, if you have no options left, it may be something to consider.
Good luck!