To effectively get rid of fleas (and yes rabbits get them that is how myxomatosis was spread through feral populations as well as from mosquito bites), you need to treat all of the environment. If the rabbit is inside a hutch outdoors then the entire hutch will need to be treated with something that will get into all cracks and crevices. The bedding will need to be changed as well. And if the hutch is off the ground then garden lime (not hydrated lime) can be sprinkled on the ground under the hutch, even throughout the yard/ garden if the rabbit is allowed to play on the lawn.
If there are any other pets in the house then they too will need to be treated for fleas, as well as all the carpets etc in the house.
A vet will be able to tell you what chemicals will be safe for use on a rabbit, different chemicals react differently in different species, that is why what is safe to give a dog, can be lethal to a cat.
Once all of these measures have been taken there is still the chance that stray fleas will be dropped in your yard/ garden by wondering cats/dogs/ native mamals that roam about at night, so your best bet would be to now use the repellents on your rabbit. Natural herbs such as tobbacco, eucalyptus, sassafras, bayleaves and vetiver can be powdered and sprinkled through a pets bedding. Although if you can get a supply of eucalyptus leaves then these can be added whole to the rabbits bedding and it wont matter if the rabbit nibbles on them. In fact many a rabbit has been cursed in Australia for eating entire new eucalyptus reforesting efforts.
Apple cider vinegar added to a rabbits water is also refuted to aid in repelling fleas, apple cider vinegar has amazing qualities for many other purposes so it wouldn't surprise me if it can help with flea control too.