Air-port express card for 5 days visit

If i will be in Hongkong for 5 days, is it possible to do the following?

Get an airport express which will allow me to;

1. Travel from airport into the city
2. Travel unlimited for 3 days

then I top-up my card as octopus for the nest 2 days,
and use it to travel from city to airport on the 5th day.