On the new pallet you add the old pallet GTIN in D8248 with "Referenced Trade Item Type Code" D3172 set to "Replaced". This ensures that the new pallet keeps the EPD number from the old pallet.
Once the new pallet has been sent to Tradesolution EPD, the old pallet will be marked as expired and the old pallet will be marked with new pallet GTIN in D8248 set as "Replaced by" in D3172: