Repartriation of Sale Proceeds of Immovable Property

"If the property was purchased using foreign currency funds from NRE /FCNR account, the maximum amount of repatriation could be the foreign currency equivalent of the amount paid for the purchase". What is the logic of not allowing repatriation of whole sale proceeds and limiting to just amount invested in foreign currency? Moreover, how the remaining balance sale proceeds can be repatriated in following future years?