You mean you don't have replacement valves!I got to 12 on one once and then the valve failed which was a shame.
Reuse old tubes for other things:
Just use a proper kit with rubber solution and take lots of care. Sand the area first. Apply solution and let dry. Apply patch and maintain pressure (a G clamp and a couple of bits of wood are good for this). I've never, ever had one fail. Maybe I've just been lucky.
Mind you I don't get many punctures. Only had one last year - and that was on New Years Day. And one the year before. The joy of Durano Plus.