In that case, the ASA doesn't support a feature that would accomplish this for you. You could look into setting up an Expect script that you can run on a PC with cron to login to the ASA and schedule a reload on a weekly basis.
I want to run a command 2 times per day at specific hour. As you mentioned, I should use cronjob in a PC to connect to ASA through SSH (or Putty). However, I cannot connect to ASA without password and I don't know how I can manage it in order to connect to it securely with password. Can you please help me?