Hope this helps....(from the House Rabbit Society)
"TREATMENT AND PREVENTION OF BLADDER STONES OR SLUDGE
Although there is no guarantee that urinary tract stones or sludge will not return after treatment, you can greatly reduce your pet's chances of dealing with a recurrence by using the following suggestions.
Increase water consumption. I consider this to be the most important factor in the prevention of the reoccurrence of bladder stones and sludge. If the urine is kept dilute, the possibility of stone or sludge formation is dramatically decreased. Feeding fresh leafy greens that are still wet from washing will help increase water intake (See note on this below). Adding a natural sweetener, not refined sugar, to the drinking water will encourage your pet to drink considerably more. Natural fruit juices with no added sugars, or honey, are an excellent flavoring choice. Test various juice flavors by administering them directly to your rabbit undiluted in a syringe. If your pet takes the juice willingly then try adding it to the drinking water. Record how much water is consumed daily by your pet (this is easy with sipper bottles as they are often marked in ounces on the outside). Use fresh flavored water daily and gradually decrease the amount of flavoring until you see that the rabbit decreases its water consumption. At this point, increase the flavoring just enough to increase water consumption again and continue to use that amount of flavoring daily. Some flavorings that people have reported success with include pineapple, grape, apple and cherry juice and apricot, peach or pear nectar and honey.
Remove commercial food (pellets)/alfalfa hay from the diet. As discussed previously in this article the level of calcium in the diet is not the primary factor in causing urinary calculi. However, excessive amounts of calcium above and beyond what the pet needs on a daily basis may add to the calcium content of the urine and be a problem in a rabbit that is already experiencing urinary calculi. Commercial rabbit diets that are alfalfa based are packed with digestible calcium and I recommend removing them from the diet. Alfalfa hay also has very high digestible calcium content and should be removed. The recommended diet for a house rabbit is grass hay (e.g. timothy,oat, or orchard grass hay) along with large amounts of fresh leafy greens, and some smaller amounts of fruits and other vegetables. If pellets are to be fed, they should be grass hay based.
Feed large amounts of fresh leafy greens.Fresh leafy greens are not only an excellent source of fluid for the rabbit (to keep the urine dilute) but also contain a variety of nutrients (including vitamin C) and fiber (for the digestive tract). Use dark leafy greens that are richer in nutrients than the pale green types. Feed a minimum of three different types of greens daily. Don䴜t stick to just one type. Examples of greens to feed include kale, mustard greens, dandelion greens, parsley, cilantro, chard, beet tops, carrot tops, raspberry leaves, broccoli leaves, and romaine lettuce.
As mentioned previously, although the calcium content of dark leafy greens is higher than some other foods, it is not all digestible and doesn't approach the level of commercial alfalfa-based pellets or alfalfa hay. NEVER attempt to remove all calcium sources from a rabbit's diet or problems with abnormally low calcium blood levels, such as bone, dental and muscle disease can occur. I do not consider feeding dark leafy greens a part of the problem causing urinary calculi, and, in fact, I consider these foods to be an essential part of a healthy rabbit diet. I do not restrict the type of leafy green based on calcium content.
Exercise. Exercise is extremely important to cause the rabbit to urinate more frequently, moves the urine around in the bladder and keeps it mixed instead of stagnant, as well as causing the rabbit to consume more water. In addition to helping with the urinary problem, exercise helps to strengthen bones and improve the rabbit's mental attitude.
Routine veterinary checkups. It is necessary to follow up your pet's progress with routine rechecks with your veterinarian. A urinalysis should be performed several times during the first few weeks after surgery or catheterization to detect any infection or increase in mineral formation. A physical examination should be performed post-surgically to evaluate healing of the bladder and abdomen. Radiographs should be performed within six months initial treatment to look for the return of stones or sludge in the urinary tract. Please follow your veterinarian's recommendations on recheck visits. "