I try to refresh my mothers every few months for exactly that reason. I lost my Sweet Tooth mom to rot that girdled the base of the stem and death followed within a matter of days. So I just take a bunch of cuttings when it's time to refresh them, and choose the most vigorous and branchy 2-4 to pot up as moms, and then pick the strongest pair later.
I keep my seeds in a cool, dark place in airtight vials.