settling timelocked contracts based on amount of time elapsed in Lightning network
Such a functionality is currently not implemented and as far as I understand not intended. You can look at Discreet Log Contracts which where intended to solve CFD (Call for difference) contracts for example with cross asset swaps and changing exchange rate within the timelock period. We have a proposal how they could be transfered to lightning. That being said this would mean severe protocol changes and also computation of many signatures. Yet I think a similar construction could be applied for your usecase.