In learning a language / improving a language I would suggest many types of activation: Listening to the radio, watching movies, reading comic books, reading childrens books, reading the news, having conversations, writing a diary, talking to yourself, keeping a running commentary for 10 minutes about what you observe - activate, activate, activate! PRing dictionaries is great, and spontaneous activation is great when it happens, however I wouldn't sit back and wait for the spontaneous activation. The more you activate manually, the more likely it is that spontaneous activation will occur.
Languages are especially wonderful, because there is so much varied material!