When prozac (fluoxetine) is tapered off after taking for a year, will it still be effective the next time it is prescribed again for relapse after some while.?

Yes: Studies have shown that restarting ssris after a period washout provide equivalent efficacy when compared to prior trials.

It likely will help: It's not uncommon to have depression return like this, especially if psychotherapy was not also part of your treatment before. Prozac (fluoxetine) may well help again, but i'd suggest seeing your physician first. If you worked with a psychiatrist before, that's the place to start. Good luck.