I think you can use - sp_update_schedule
to update the schedule.
sp_update_schedule { [ @schedule_id = ] schedule_id | [ @name = ] 'schedule_name' } [ , [ @new_name = ] new_name ] [ , [ @enabled = ] enabled ] [ , [ @freq_type = ] freq_type ] [ , [ @freq_interval = ] freq_interval ] [ , [ @freq_subday_type = ] freq_subday_type ] [ , [ @freq_subday_interval = ] freq_subday_interval ] [ , [ @freq_relative_interval = ] freq_relative_interval ] [ , [ @freq_recurrence_factor = ] freq_recurrence_factor ] [ , [ @active_start_date = ] active_start_date ] [ , [ @active_end_date = ] active_end_date ] [ , [ @active_start_time = ] active_start_time ] [ , [ @active_end_time = ] active_end_time ] [ , [ @owner_login_name = ] 'owner_login_name' ] [ , [ @automatic_post =] automatic_post ]