This is the second time I have washed my BTSSB Masquerade Theater jumperskirt (jsk). The first time mortified me a bit because some of the detailed bubbles were fading for sure because I thought it would be bright to let the jsk steep in water and detergent for 15 mins. I wash in cool water so thankfully I didn't screw myself over much. I did a search for clothing care and found on EGL that vinegar preserves prints. I wish I knew that first but when I learned that, I took some apple cider vinegar, mixed it with water and pretty much bomb my dress as it laid on the rack. I would have added the vinegar to the water as I washed it buuuuuut I was still checking sources so I had just taken it out when I finally figured out that my dress could really benefit from vinegar. Hopefully that'll make things ok.
One thing I don't like about brands such as BTSSB is that for all the money you pay them, your stuff should be colorfast and very durable instead of buying prints that melt in the wash or run like crazy. My Anna House dress (my dream dress) washes tons easier than my BTSSB dress. I don't have to worry about running prints or anything. My BTSSB is so much hassle, it almost makes me wish I didn't have it because I have to worry about the corsetting, the print running and the lace breaking. Already one piece of lace is slightly ripped in the back because of the lacing up and I can fit brand fine. The Masquerade Theater dress is very beautiful, that's fact, but it's high maintence too. It's a good thing I don't have the Navy one because I heard too many horror stories about the darker colors running and ruining the print. That's horrible. A $300 dress that can destroy itself. If this is how the top lolita brands act, I'll stick with the Chinese ones. (Except for Putumayo, I love Putumayo.) I'll save money and hassle.
-put a cup (to the gallon) of vinegar when you are rinsing your clothes. -apply some laundry detergent or shampoo at the neck and sleeves of you blouses, leave it for 30 ...
Ok, I tried the vinegar, water, detergent solution on my Aatp dress that I had to wash. The colors came out and bled like your dress did. But after I did it a second and third time, it turned out fine. Now it's good as new (and clean too). Let me know if this method works for you~!