Rabbits do not go into heat like other mammals. Rabbits are in almost continual estrus until they are bred. HOWEVER, the length of daylight hours will also determine the breeding receptivity of the rabbit does. Short daylight hours (winter) will make does less receptive. You can put lights in your rabbitry and leave them on to crete a false longer day. This helps. Heat will make older rabbit bucks sterile until the temperature drops for a few weeks.
Several things to determine:
How old are the rabbits?
Are you sure that they are not both does or both bucks?
Older does 11-12 months and older do not always breed as easily as younger does. You have to remember that a rabbit is relatively short lived and that they are begin to breed and produce at 6 months old. They are at their most fertile time to rebreed about 3-5 days after kindling. In a production rabbitry you should keep all does bred, kindling, and lactating at all times. I used to rebreed my does when their kits were 4-6 weeks old so the does would kindle again within 2 weeks after their last litter was removed. Around 3-4 years the size of litters drops, the doe may not take every time, or she may not be receptive to the buck. Around 5 years old her productive life is pretty much over if you are breeding her for meat production.
Make sure to sex both rabbits and make sure that his penis and her vulva are clear of any inflammation. Normally a clean vulva that is bright red can signal a receptive doe. However, any scaly debris around her vulva and his penis might signal vent disease. Did you get these rabbit as kits, or were they adult breeding age rabbits? I bought a Grand Champion buck from an out of state breeder for a large sum one time. Then I found out that he was not an ethical breeder. The buck he sold me had vent disease - rabbit syphilis. Vent disease does not show signs constantly, it comes and goes but is contagious at all times. By the time I found that my beautiful champion had vent disease, I had bred him to most of my does. I ended up having to euthanize/get rid of my entire flock of Holland Lops.
Depending on what the problem is with your doe's distaste for breeding, first I would put lights over the rabbit cages to lengthen the "daylight hours". Then if she is still not interested in lifting for the buck put her in the car and take a drive around for about 15 minutes. When you get back immediately put her in with the buck. No one knows why, but this little car ride seems to make the does more receptive.
Hopefully this will work.
