My rabbit has very bad cecal dysbiosis but it is currently well controlled. Here are my suggestions.
Start by going to an all hay diet for a minimum of 2 weeks. You do have to watch your bunny closely during this time since she isn’t a great hay eater to make sure that she is eating enough. You can also purchase pellets that are made of 100% hay with no added ingredients to supplement her diet. Not sure where you’re located but I use these (pictured below) in the US.

After at least 2 weeks but preferably 3 or even 4, you can slowly start reintroducing foods to her diet. Many rabbits will have no further issues after a few weeks on hay only. Some rabbits are very sensitive though so you will want to reintroduce one food at a time in small quantities and watch for issues. Stick to low sugar items only and start with easy to digest things like maybe romaine.
If your rabbit continues to have mushy cecotropes then try to identify if it’s a single food or if it seems to be caused by everything. Unfortunately my guy seems to have problems with just about everything that isn’t dried and sugar free so on the advice of his vet I got him a bunch of dried herbs to give him some extra flavor and nutrition. I buy him bulk herbs and he particularly seems to like sage, mint and dandelion greens. He hasn’t had any issues with the dried herbs.
Another thing that can help in some cases is to feed her digestive treats (pictured below) and/or benebac after her hay only period is up.

(Edited by Wick – shop links removed and replaced with product images)