Backup and Restore Single App After Upgrade
If it's a built-in Apple app, then no.
Otherwise, just don't update that app when asked.
Eventually, though, you will get to a point where the old version may no longer work on the new OS.

Check that you don't have automatic downloads set in Settings > iTunes &amp; App Store, then non-Apple apps will not update until you tell them to, from App Store app itself.