Recovering D: drive and I have two D: drive files.. How to do this??

I created a backup image of the D: drive on my server 19 days ago.  Then I did another backup for the D drive 8 hours ago.  I think that it only backed up what had changed on the D: drive because the image is much smaller.

We are putting larger drives in for the second array.  Currently I am doing a recovery using the backup image from 19 days ago.  How do I do the second recovery from 8 hours ago to just update the files that were changed??

Hope this makes sense.

Am doing this right now so any assistance would be appreciated.

Thanks

Cathy