If a parent wants to opt out services on an IEP that is already in place dated 10/23/2023 to attend private school, will the IEP still be good the following year? This is the state of Kansas 

I'm not fully understanding your question.  Are you looking to keep the private school placement but waive a service in the IEP - it might be possible.

Did you say no to an IEP dated 10/23 and now want to get what this IEP says your child needs?  After this length of time and with no progress monitoring, baseline/present levels need to be updated so the school would likely want to evaluate before reinstating an IEP.  They might be OK with using the old IEP while they do evals or they may want the student in gen ed since there is no longer an IEP identifying them as disabled.

Or are you asking if the IEP will be good after the student has been at a private school for a year and returns to the public school?  The IEP does not follow a child to a private school.  In some instances, the district in which the private school is located may provide some services, but they would not be as robust as under an IEP.  Since you are voluntarily placing your child in a private school (as opposed to an IEP team deciding on an out-of-district placement), you are correct that you are "opting out of services," and I believe upon the return to public school you would need to start the process all over again to determine if services are still needed.

Okay, thank you! That's what I thought the process would have to start over.