By Sue T
Make sure you let it completely dry out before re-caulking. I have used bleach before and it worked. In your case if you have used bleach, let completely dry out before re-caulking then you need to go buy a mildew(mold) killer. At the hardware store mold be gone, or other products can be purchased.
Usually people use these in areas like mine , close to water and damp. They have same products to use before painting. It works before caulking doing the same thing. I have to use a product called Damp Rid (daily) it absorbs extra moisture in air,in closets so make sure the bathroom has a good ventilation either window or air vent. If extra moisture is on walls, floor, etc. a product like Damp Rid (charcoal works) needs to be used. Only the shower? Get product you use before caulking. Kiltz It is also one used here.
Make certain your caulk is applied properly ... so that water can't get behind the caulk. Leave NO cracks for water to get into. After showering, take your bath towel and dry the shower. Paying special attention to where the mold was. This will eliminate mold/mildew reappearing. It only takes a few minutes to dry the shower,but will save much time, trying to remove the mold/mildew!