Let’s say there would be two thresholds, for instance 80% and 30%, and also a max limit (and maybe a minimum limit too).
If a belt would be mined beyond the upper threshold, the next time it spawns, it would spawn less minerals (depending on how high it was overmined). Any time it is under the lower threshold (but equal or more than 1%), it would increase the difference between the mining amount and the threshold. Note that if it is between the two, it stays so.
So if a corp would need lots of minerals to replenish their stocks fast, they would be able to overmine, but that would reduce the amount next time.
Also, if enemy Prospects or other miners would sneak into a region inhabited by their counterparts, they would be able to ninja mine and actually damage the economy of the other corps by decreasing their gain from the belts. That would be an offensive way to use miners, greatly enhancing their role in wars, and as such, it would result in a more interesting gameplay and new options for corps and alliances to consider.
I mine out entire belts myself every day. New players already have enough trouble even finding ore in high sec and especially low sec as it is due to NPC mining fleets. We’ve already done the miner wars / resource scarcity thing before. No thanks…
Unless something changed with all the other changes too mining then there is already less ore in a belt the next day proportional to how much was mine the previous.
Basically each day each belts add more ore (up to a limit) so a belt that ended with 20km3 left in it will have more the next day than a belt that was picked clean.
However this doesn’t apply to anomalies only belts.
I don’t think your extra bit of complexity you want to add will actually bring anything to the game outside of the tedium of constantly checking the m3 left in a belt and new players getting berated/ kicked from corps for not paying attention.