Upon the admission of a new partner, any upward revaluation adjustment (increase in the value of assets) is directly debited to:

When an asset increases in value, the asset account must be increased. In double-entry bookkeeping, an increase in an asset is recorded as a debit. The corresponding gain is credited to the Revaluation Account (also known as the Profit and Loss Adjustment Account).The accounting journal entry is:
$$\text{Asset A/c}\text{Dr.}$$
$$\text{To Revaluation A/c}$$
Therefore, the increase is debited to the respective Assets account.