How to update data classes implementing a common interface

I'm struggling with data classes and polymorphism. I want to benefit from the immutability, but still be able to update my state. For this, I'm hoping to be able to use the copy function.

Let's give an example. I have this class hierarchy:

interface Aging {
  val age : Int
}

data class Cheese (
  override val age : Int
  // more Cheese specific properties
) : Aging

data class Wine (
  override val age : Int,
  val grape : String
  // more Wine specific properties
) : Aging   

And now I want to be able to do something like this (but this does not work):

class RipeningProcess(){
  fun ripen(products : List<Aging>) =
    // Not possibe, no copy function on Aging
    products.map { it.copy(age = it.age + 1) } 
}

How can I create updated copies in a polymorphic way?

I've tried to give the interface a copy function, but if the subtypes have additional properties they don't override the copy function.
It's frustrating since I know the subtypes have that property, but I cannot utilize that knowledge in the interface.