Hi venkata,
Redisaggregation along with other few options have been added in SCM7.0 release. It is basically used to recalculate key figures that were disaggregated on the basis of another key figure. Also this can be used only for the key figures that are set as 'Fixable' instead of 'Simple' in the planning area settings.
It basically helps like consider a scenario where you have set Key Figure A to disaggregate based on Key Figure B in planning area - key figure settings. Now if you change values in Key Figure B, system won't automatically change values in Key figure A as it will still be based on previous entries. In this case, if you execute macro using Re- disaggregation mode, Key figure A will also be disaggregated in same proportion.
Hope it helps you.
Regards,
Alok