When you reignite a fire in game the temperature of the fire never gets above the starting point of the fire once relit. Will not give heat-buff, allow cooking, or dry cloathing.
For example, if the fire temperature drops to 100C after going out and then being relit,the fire will never get above 100C after it is relit. This is regardless of the amount of wood added or how long the fire is kept going. Until the fire completely goes out and is lit from scratch the temperature will never increase.
[[ https://www.youtube.com/watch?v=fsn7ohVFpkQ | Video Example]]