Unfortunately, "cure" may not be possible. "Control", however, may be a much better description. It's all about finding what works for each pet.
IBD is an inflammatory condition of the bowels that commonly results in symptoms that vary from chronic GI upset to diarrhea. This is why your vet has recommended I/D and W/D. Many of these types of bowel issues are responsive to fiber. It's been my experience that a totally different approach, one with limited ingredients, more protein and less fiber, tends to yield better stool quality that's more dependable. That said, in many cases, we have to stick 100% to a diet that works (can can't add in new things like apples or blueberries no matter how much the pet enjoys them).
I would recommend looking at balanceit.com and working with them, along with your vet, to formulate a diet for Lexi that is contains novel proteins (turkey, duck, quail, trout, swai, etc), carbohydrates (pumpkin, quinoa, etc). and giving this type of diet a try for a few weeks. These types of diets tend to make it easier to modify small things in the diet until the stool is nearly perfect. In some cases of IBD, a removal of carbohydrates can produce a more firm stool. This may be needed in her case since she's having some stringy appearance to her stool on a more fibrous diet.
Did my response help to answer all of the questions that you had regarding your companion? If you have other questions, please reply and I’ll help you further.
Once you're satisfied with our dialogue, please take the time to use the star rating system at the top of the page to leave a rating for me. Until this is done, the website will not compensate me for helping you.