You can buy tubes of Rema "glue" separately. They come in 5 gm and 10 gm sizes. I found that 5 - 5 gm tubes lasted me 2 years and 200 patches. I opened only 1 tube at a time. I was also careful to close each tube as soon as I spread the vulcanizing fluid over the puncture.
One caveat. The can and the tubes are different products.
http://www.rematiptop.com/technical/...03_204_205.pdf
http://www.rematiptop.com/technical/...id-201_202.pdf