Do I need to backup a wallet every time I generate a new address? This question concerns the Armory client.

Since Armory has deterministic wallets, do I only need to back up a wallet one time (after creation), or do I need to back it up each time I create a new address with that wallet?

In other words, can all addresses, that a deterministic wallet creates, be recreated again if I lose these addresses, but still have a backup of the "genesis" wallet (I assume that, in this context, that is meant with a deterministic wallet, correct)?
When you generate new accounts inside a wallet you will only have to make a back-up once. The backup key gives armory the possibility to create a indefinite series of addresses for your wallet.

Please note that by default, Armory only generates 100 addresses. This means that when you use more than 100 and you lose your wallet, after you restore the back-up, the client will at first only see the first 100 addresses. You will have to specifically tell Armory to look for more addresses.

This does not count for addresses you imported in a wallet! If you import private keys to a wallet, you will have to back-up them separately! The easy back-up process only works for addresses generated by Armory.