Vegtech has it exactly right!!!
As a very experienced IP water pourer (from my Suburban a few years ago) it doesn't take a ton of water, just pour slowly in the right place so it splashes the pump, and don't wait long before trying the restart. A 16 oz. water bottle was enough, poured slowly, then started right up. I did that for months. Cold starts were fine, warm starts within 20 minutes were fine, but between then and maybe an hour, 90 minutes in the summer, and it wouldn't start without the splash.
It probably won't die suddenly, so cold starts will get harder and you'll know you're near the end. Gotta love DS-4 pumps!