Workaround: To replace lost time, first have the player craft a new Time in a Bottle, or give them one. Then, use NBT Explorer to access their playerdata (saved under their UUID and found in the /world/playerdata/ folder). Find their inventory, then the Time in a Bottle item. Edit the correct NBT tag to reflect how much time was lost. 15 hrs is 1,080,000 ticks.
Link to reported issue: https://github.com/lumien231/Random-Things/issues/430
Workaround: To replace lost time, first have the player craft a new Time in a Bottle, or give them one. Then, use NBT Explorer to access their playerdata (saved under their UUID and found in the /world/playerdata/ folder). Find their inventory, then the Time in a Bottle item. Edit the correct NBT tag to reflect how much time was lost. 15 hrs is 1,080,000 ticks.
Source: https://www.reddit.com/r/feedthebeast/comments/bibicw/e2e_lost_my_time_in_a_bottle_any_way_to_get_back/elzdffi/