Once you've learned to speak and understand Hebrew, even little (or any other foreign language for the matter), you have to keep on using it frequently or you will forget it soon. That is what i'm told.
As we have a bilingual country, my mothers language is Finnish and secondly Swedish. My English is somewhat ok (could be better) and i can make myself understood (at least most of the time) with German and Estonian. Foreign languages do not vanish if you keep using and practicing them.
I once planned to learn Russian. Not because i needed it but just because it is the most beautiful language i know. My friends wife who works as a German and Russian teacher said i shouldn't bother. It is all in vain if i'm not going to use it (or then it was just the polite way to say that i have no talents :D). Nowadays i just try to improve my German and Estonian (and there surely is a lot to improve).
Anyways: Good luck with Hebrew. I've never heard anyone speaking it. Hope we will fix it some day.