Hi Ujjawal,
I also faced the same problem,
What i do for this i will share with u,
U also Try and Let me know if its working or not
1. Load the table, make the report then save it.
2. Open new report > Click On Add Data Source > Add your new Excel with changes > Give the same name > Refresh the data
3. Close the new report > Open your Old Report > Refresh the Data.
this steps work fine for me..
Thanks
Vicky