I create SQL to insert forecast to item but I need to insert more than one month to the same item

I create SQL to insert forecast to item but I need to insert more than one month to the same item

set serveroutput on

Declare   

t_forecast_interface_tab    MRP_FORECAST_INTERFACE_PK.t_forecast_interface;   

t_forecast_designator_tab  MRP_FORECAST_INTERFACE_PK.t_forecast_designator;   

var_bool                    BOOLEAN;

begin   

t_forecast_interface_tab(1).inventory_item_id := 1824;   

t_forecast_interface_tab(1).forecast_designator := 'Qtest';   

t_forecast_interface_tab(1).organization_id := 83;   

t_forecast_interface_tab(1).forecast_date := '01-MAY-2017';   

t_forecast_interface_tab(1).bucket_type := 3;   

t_forecast_interface_tab(1).quantity := 273000;   

t_forecast_interface_tab(1).process_status := 2;   

t_forecast_interface_tab(1).confidence_percentage := 100;