Change reconnection timeout from 9 minutes

Is there a way to change reconnection timeout which is 9 minutes currently to any other value, say an hour

No, but you can implement your own reconnection scheme which behaves however you want by using RETURN_ON_ERROR and your own application logic?

There’s more information on making use of the RETURN_ON_ERROR policy in this Developer Guide an in the imp WiFi State Diagram, @shatruddha.