Dear Duy
You can set as follows
1. GO to MM01 for your FG then set the required value at Accounting1 tab field Future price & valid from.
2, Go to t/code OKKN & choose your costing variant then goto tab valuation variant - priority 1 - set
Future price from accounting
3. You can create another costing variant
4. Before process you have to deleted existing costing run for the period which period you have to update if required against material only though CKr1.
Regards
avijit