Hi @aherrera,
Unfortunately, just like @Pstork1 said, the mix duration is 1 month, there is no way to extend the Flow run time to 3 months.
According to your requirement, maybe there is a workaround that creates a recurrence trigger run every 3 months to send an approval request. Recurrence every 3 months -> check the File whether still exist(compare with the file list or other things) -> Send an Approval.
If you have a detail description of your requirements, it will be better for us to assist you, thank you.
Best Regards,
Community Support Team _ Lin Tu
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.