Half yearly frequency on HR leave module not automatically assigned after half year

I have created a employee on ERP next and created a leave type earned leave with half yearly frequency and create a policy with that leave type . First 15 leave allocated to employee on first half year of the session but next 15 leaves are not allocation automatically to employee after half year.

Do I have to set any CRON job for that. OR any other thing.
Please suggest me solution.