日付変更手数料(スターアライアンス世界一周航空券)

明記されていますが

Change of plans

Prior to Departure

Changing travel dates/carriers/flights leading to rebooking/revalidation
of any sector is free of charge.
Changes that require a rerouting will result in a fee of USD 125.00 per case.

After Departure

Change of travel dates, carriers or flights is free of charge.
Changes that require a rerouting will result in a fee of USD 125.00.

Exception: In the event of death of the passenger, members of the passenger’s immediate family or accompanying passengers may reroute the remainder
of the journey without charge. Relevant documents will be required.

読めばわかりますが、同じルートであるかぎり、無料です。