Repetition is essential to remember words over the long run. This is not easy to implement, but with a little discipline and organization you can make it work. If you are using flash cards, make it a rule to go over the flash cards you mastered for example after one week, then one month, then six months. It is not a big job to repeat flash cards you are supposed to know, and you should know have the fear that you are opening a can of worms that will undermine your confidence in your existing knowledge of the language. The only thing you will achieve is to reinforce your vocabulary skills. It is not uncommon for people to master perfectly a list of words for a school exam, then forget most of them after a few days. That is not problem is all you want is pass a school exam on a specific day, but if what you want is learn a foreign language, you need more.

If you learn new vocabulary with a newspaper and dictionary, it is a good idea to go back to last month's articles with no dictionary and see how much you understand.

If you are learning with Pimsleur, the tape will take care of the repetion as it is a basic principle of their system, called timed interval repetition. Words learned with Pimsleur usually stick to your memory, provided you do one tape a day.