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]
source share