Just my two cents since I've had an on again, off again struggle with vapor's tongue.
1. Unflavored juice. You can easily DIY that. Its base and vg or pg. I tend to prefer PG. You get the act of vaping, and the nicotine, but if you don't taste anything it is because there is nothing to taste.
2. Prepare a mouth rinse for yourself using the following recipe, 1 teaspoon of baking soda and then 4 oz of water. Dissolve the baking soda completely (just like you would if you were going to drink it as an antacid). And use just like you would with mouth wash. The salty-bitterness of the baking soda seems to wake the tongue up. I would not recommend using a mouth wash with alcohol in it, and I've not tried biotine.
3. vaping the same thing all the time becomes background noise to your tongue. You may try to change up your juice. For example I vape a cowboy type a lot. When It gets to where I can't taste at least the "tobaccoy sweetness" from it, I switch it up.
4. If you can smell your vape, but not taste it (commonly my situation) get a juice that smells really nice to you and enjoy the odor rather than the taste. Strangely taste and smell are closely tied.
5. Change your tooth paste. I usually use a cinnamon tea tree oil herbal tea, but found that I when I had/have vapor's tongue I prefer a lemon hyssop Colgate variety (strangely I hated that tooth paste when I was a smoker but like it now...go figure).
Above all drink lots of water. I've actually measured my water intake and I need to drink at least 3 liters of water to keep from having vapor's tongue.
ETA: I've also found that some kinds of water based beverages without caffeine also helps clear up a condition similar to vapor's tongue which is really the juice coating the tongue, and that is to use like a crystal light lemonade or fruit punch seems to break up the pg or vg better than just water.