XBEE ZB Child Poll Timeout

Hello all,
I’m working in AT transparent mode, the end device is in pin sleep mode, and the sleep period is not known: it wakes only when the user presses a button. Maybe once in a year, just to say. I’ve set the Child Poll Timeout on the coordinator as long as possible. But what happens when it runs out? What happens if the child wakes and sends some data? The data will be lost? The child will attempt another connection? Or the serial connection will stop to work definitively?
Thank you very much.

The end device will have to rejoin the parent node before the data can be sent.