On the death of an existing partner, in case the value of a Liability decreases then which account will be debited?

A decrease in the value of a liability is a gain for the firm. At the time of reconstitution due to the death of a partner, assets and liabilities are revalued through the Revaluation Account (also known as the Profit and Loss Adjustment Account).To record a decrease in liability, the journal entry is:
$$\text{Liability A/c}\text{Dr.}$$
$$\text{To Revaluation A/c (or Profit \& Loss Adjustment A/c)}$$
Hence, the Liability Account is debited.