GR agnst Process Order-Filed Overflow Error

Hi SAP Guru's

We have following ML concept in my company - when i Post GR Against Process Order I got this error filed Overlap , I know this error why it comes because of in Material Master PUP Price too High,That's why I want Change PUP Price Material Master in Month Middle can please help me how to resolve this issue.

Please provide me Steps for Changing PUP Price in Material Master.

Thanks,