Yes, in your case you would need to backup any data created or changed after the backup image was created, before you restore the image.
You would then need to restore these data files after restoring the backup image.
I'm assuming all your data is stored on the C: partition.
Most tech enthusiasts keep data on a different partition than the C: (OS + Programs) partition.
This approach allows restoring the C: partition independently from restoring or keeping any data.
Imaging is the best option for backing up the OS partition, but is not the best option for backing up data.
It's also recommended to store backups on more than one Hard Drive (or media).
That will allow recovery from a Hard Drive crash.
Also, I prefer Acronis or Macrium over the Windows Backup program.
These programs are easier to use and have more flexibility.
Some stickey threads you should take a look at: Imaging strategies Image your system with free Macrium
There are also some SF tutorials for Backup and Restore.