How can i extend my pickup date for books on hold?
No, unfortunately there is no way to do that; the reasoning is that would make the wait for holds even longer, especially for popular items. However, you can reserve it again as soon as your hold expires, and if no one else is waiting for it, it will be back on the shelf for you almost immediately.
In addition, if you are going to miss your final pick-up date by just a day, you can always try calling the desk at the branch where you pick up your holds--if there are no holds on the item, they can usually keep it at the desk one more day.
I hope this answers your question! Let us know if not.