Well the key to that, and I am guessing you didn't this time. When you get Isos you don't buy just to seed the tank. Buy to start cultures and seed the tank at the same time.
Get some shoebox sized Tupperware and make a master culutre of each. Then seed some of those into a tank, not all of them. That way you always have isopods and springtails, for other tanks and for instances like this.
If you keep your bugs with substrate (I think you should) the isopods and springs are useful there as well.
