The property management may allow you to do this. When I had a canceled flight, I was able to do this. If doing this for convenience, I think they are likely to be more willing to give you the later arrival data at the same rate if the rate the LNF was based on was one that did not require the longer stay. As far as I know, only the property itself (at their discretion) can make any changes to this type of reservation and maintain your discounted rate.

In my experience, CC has been unwilling to change the duration of a LNF reservation.