Over the forty years I've suffered from depression, we've tried everything. Some things worked, but only for a while; then they stopped. Is there any hope for me?

I would ask some details as to the characteristics of your depression, and what exactly you have tried. All too often, trials of antidepressants are set at dosages that are too low to be effective, and/or the medication is tried for too short a time. When, of course, the patient doesn't respond, frequently hir depression is labeled "refractory", when it is merely under-treated.

If the medications you have tried were administered in suitable dosages and durations, I might ask if you have tried an MAOI. Sometimes this class of medication proves useful where others have not.
As you report that some things worked for a while, it may be possible to try a medication that was at least briefly effective in combination with another medication(s). Combining antidepressants, or, an antidepressant with another medication such as a mood stabilizer, an anticonvulsant or an antipsychotic may have a boosting effect.

Another thought is seeking Electroconvulsive Therapy (ECT). This is much-maligned and feared but is actually a highly-effective treatment for refractory depression. The success rate of 85% to 90%  often more than offsets the slight risk of some memory loss.

Some persons with depression for whom  medications and ECT do not work may find that certain types of cognitive therapy are helpful. Some, however, find that the cognitive fogginess and demoralizing aspect of their depression precludes progress. It may, however, be worth a try.

I find that it is increasingly common for the psychiatrist or patient to ask for a second opinion. This should not be viewed as an admission of defeat. Rather, it is an opportunity to review treatment from a fresh perspective. For this second opinion, you will want a psychiatrist with special expertise in psychopharmacology.

It may behoove you to participate in research of the latest potential treatments.  Listings of current and upcoming studies can be found on the Internet, at addresses such as:
http://www.clinicaltrials.gov and http://www.centerwatch.com.

Your endurance in this struggle with depression is remarkable, and I urge you not to give up. There is indeed hope.