Updating certain fields in Table

Hello Experts,

I am working on the program used to calculate renewal price of an equipment based on CPI and acquisition price. There is Custom field defined in table EQUI for renewal price (ZZSTOFN_VERD). I have used BAPI_EQUIPMENT_SAVEREPLICA to modify the table as per renewal price. There is no field available in BAPI for Renewal Price so i have used Acquisition Price field for trial basis and it worked. Now what i want to do is instead of Acquisition Price the Renewal Price should be updated in Renewal Price field (ZZSTOFN_VERD) of table EQUI. Here is the code below,

Data:  l_tab_equi  LIKE TABLE OF l_str_equi,

          l_str_equi  TYPE l_str_equipment,

          l_str_equip TYPE bapi_ieqm_extractor,

          l_str_equix TYPE bapi_ieqmx_extractor,

          l_tab_equip LIKE TABLE OF bapi_ieqm_extractor,

          l_tab_equix LIKE TABLE OF bapi_ieqmx_extractor.

LOOP AT l_tab_equi INTO l_str_equi.

       MOVE l_str_equi-equnr TO l_str_equip-ta_guid.

       MOVE l_str_equi-equnr TO l_str_equip-equipment_int.

       MOVE l_str_equi-equnr TO l_str_equip-equipment_ext.

       MOVE l_str_equi-eqtyp TO l_str_equip-equicatgry.

       MOVE l_str_equi-eqktx TO l_str_equip-descript.

       MOVE l_str_equi-invnr TO l_str_equip-inventory.

       MOVE l_str_equi-ansdt TO l_str_equip-acqdate.

       MOVE l_str_equi-answt TO l_str_equip-acquisval.

*      MOVE l_str_equi-newwt TO l_str_equip-acquisval.

*      MOVE l_str_equi-newwt TO gs_equi-ZZSTOFN_VERD.

*      APPEND gs_equi TO g_tab_equ.

*      UPDATE equi FROM TABLE g_tab_equ.

       MOVE l_str_equi-waers TO l_str_equip-currency.

       APPEND l_str_equip TO l_tab_equip.

       l_str_equix-ta_guid = l_str_equip-ta_guid.

       l_str_equix-acquisval = 'X'.

       APPEND l_str_equix TO l_tab_equix.

     ENDLOOP.

I really don't understand how to achieve this using BAPI? If anybody have any idea please share it with me.

Thanks,

Avadhut