automatically build cube

[????]

Hi all:       In my fact table, it have data between 3/24 adn 3/30. When I 
create the model, I choose the starttime column(yyyyMMdd) as the partition date 
column. And I build the cube with data of date 3/24 at the time 5/14 23:18, 
after two days, it doesn't run any job to build cube again.
       How can I enable the automatically build function.