"I’ve read about vaping using the temperature control to get the compounds that you need, but what about the remaining unused compounds? For instance, let’s say I use my vaporizor with the right THC:CBD cannabis ratio for sleep at night, and set it at about 400 degrees… would the unused compound THC-V remain in my vaporizor for use the next day? Would I be able to re-use the same material and vape at 428 degrees to take advantage of the THC-V for the anti-inflammatory properties and appetite suppressant? "
If you have not vaporized them yet the compounds are still there. Those temperatures are not as hard of a limit as you describe, however. In a perfectly isolated simulation the difference between 427 and 428 degrees means that all of those compounds have been left untouched, but, because we are in a dynamic environment, things are not so clearly outlined. A lot of vape devices have a chamber that creates suction, i.e. a vacuum, which will change the boiling point of those compounds. Other factors in your space, like altitude and humidity will affect things as well (Water boils at 212F in Death Valley, but at 202F in Denver). You can still vape that cannabis and get those compounds from it, but it will be a diminished experience.
You will find much more usefulness from your already vaped bud (AVB) through making tinctures or edibles. Check out some great ideas here: https://www.hellomd.com/answers/57719957a923a4000b0001c4/what-do-i-do-with-the-flower-i-vaped
If it’s unused it can be used again until it becomes a black fine residue,,Use Indica to help sleep and relax and use Sativa for a more alert focus and upbeat..