On the admission of a new partner, an increase in the value of assets is debited to:

When a new partner is admitted, assets are revalued. An increase in the value of an asset is a gain for the firm. To increase the value of an asset, the respective Assets account must be debited, and the Revaluation (or Profit and Loss Adjustment) Account is credited.The journal entry is:
$$\text{Asset A/c}\text{Dr.}$$
$$\text{To Revaluation A/c (or Profit \& Loss Adjustment A/c)}$$