Hi Roni! If a script is not a workable solution, it might fall to just making it part of your GM patter: "Go ahead and take a long rest, and remember to deduct your rations". As to the larger question of "why does this not exist?" is likely because there is not a universal need. Many groups do not play a subsistence style, or decide not to track rations at all, or just deduct a gold piece value from their characters for "living expenses". They might even go the opposite route and find that "per long rest" is not grainy enough and account for every meal. Or individuals may have classes or races that do not need food or water and would find an automatic system to be detrimental. There are also several places on the sheet (I am presuming that this is in reference to the D&D 5th Edition by Roll20 Sheet, but that's a tenuous assumption) where rations could be tracked, that would make automation impossible. In other words, the sheet provides general features, whereas you need a specific solution to a specific problem. If the sheet addressed that specificity, it would probably not be appreciated by many other users. There are many ways you could automate this, but they all require a certain amount of individual customization. Personally, I think that if you don't have the time or inclination to dive into a scripting solution, that's perfectly understandable--you're here to play a game. But then a manual reminder is probably best.