At the risk of telling you things you already know and/or find useless: when it is necessary to keep talking even though voice loss seems imminent (which, for my day job, is common, since I am literally paid for my ability to talk nonstop), I find that throat coat tea is invaluable. We captioners swear by it. Coconut water is also helpful (despite being trendy) - it coats better than water, without being sugar sticky like juice or full of protein strands like milk.