As per my Knowledge

1.you test application multipul test data.
2. With out Connection of database
3. Data use multiful time..

For Regression Testing we will use Automation .

Example :

just think as you are working on Maintanence project

Suppose u executed ur testcases on one load
After one load got released successfully then next load 
started (Ie : for each new load,new features will come to 
the picture (New change requests))

So you will do manual testing for these new features,
and at the same time you have to prepare the script for 
past load testcases .

I think you understood ...in our project we are proceeding 
in this way...