My cucumbers peter out in the fall, but I've always assumed it was mostly due to cool nights and mildew.
But I had to go looking and found this article
https://homeguides.sfgate.com/long-c...ive-58721.html So it sounds like the normal life span of cucumbers is not all that long. Jeannine - maybe yours are just normal and you need to start successive staggered batches? I start some early to set out as plants, and then plant more seeds where I think I have gaps, but have never kept track of whether the younger plants live and produce longer because they all get taken down by fall mildew anyway.