SAP CRM Marketing: Update Target Group Daily in a batch

Hi

We are on SAP EHP1 for CRM 7.0.

I have created a target Group, and my Segmentation BASIS will change everyday.

So I need to update the Target Group everyday.

For e.g. I have 30 BPs in Segmentation BASIS today and 10 in my Target Group, based on some filters.

Tomorrow I will have 40 BPs in the Segmentation BASIS and say 15 in Target Group.

I am trying to update the Target Group in a batch, but its not working.

The number of BPs in the Target Group remains the same, even when the Segmentation BASIS gets updated with new BPs.

Am I missing anything?

Please help.

Thanks

Gaurav