My Vine is looking a little 'crispy' - advice?

Hello All,

My Passion Flower that was doing so well a few months ago, has taken a turn for the worse and I wondered if you could help? I started having quite a few dead leaves which then turned into whole stems dying. Some even had unopened flower buds! I've had quite a large cat population on this plant, so I've sprayed it with cat killer and also re-added a systemic furtilizer. So that could be one issue - but the systemic is not new to this plant so it would be weird if that was the reason. Secondly, our weather is changing so I decreased the watering which perhaps affected it. It's on the same line as many other plants, so if this is a plant which needs a lot of water I'll have to hand water it for fear of rotting the others if I turn up the sprinklers. I didn't think it was decidious, but perhaps I'm mistaken? Please advise.

Thanks much, Christina