Thanks for the reply. I decided against going forward with this as every option seemed to involve reinitialization of the subscriber. On top of that Microsoft does not support adding an identity column to a published table:
"Adding an identity column to a published table is not supported, because it can result in non-convergence when the column is replicated to the Subscriber. The values in the identity column at the Publisher depend on the order in which the rows for the affected table are physically stored. The rows might be stored differently at the Subscriber; therefore the value for the identity column can be different for the same rows."