I lost a number of young plants last year during the 3rd quarter of the year and just another recently. Interestingly, the weather is turning cooler (77F) and the relative humidity averages around 85-90%.
All of the plants start by stopping their growth, followed by loss of dew over the next 1-2 weeks and finally they dry up as if there is insufficient water.
Should I reduce watering dramatically in such conditions and leave them to absorb moisture from the air?
Currently, they are in individual 3" peat pots and watered every two days as my growing area is windy. There isn't any direct sunlight but I could put them under T5s if needed.
It sounds like your plants are entering dormancy. I'd keep them much drier and let the soil become just barely damp to the touch. And yes, I'd put them under lights as well, since the lack thereof will cause fungal root issues during dormancy. Interestingly, my plants enter dormancy during the hottest months (June-September), then re-awaken in the Fall and Winter!
I've always grown these in a very sandy mix (50% peat 50% sand) and never kept them saturated or standing in water for extended periods during active growth OR dormancy. They seem to appreciate things drier than other Byblis forms, in my conditions.