You will need to step it up. The cost of DME in the grand scheme of things is negligible compared to buying more yeast. And cheaper than buying more yeast, even dry. Of course, if you brew AG and buy in bulk it is even more so. As you can just either use the last runnings and can, or brew up a weak wort and can for starters. Or forgo that link and go to the other one that is stickied, and slant the yeast. Then you'll never run out.