Could we slow down life?
Short answer: Changing something (instead of everything) yes.

There are several studies on the impact of environmental factors on life span.
Of course it depends from organism to organism. Diet restriction for example has been shown to extend life span of worms and mice. Temperature is also working well, at least with microorganisms, the metabolism of E.coli for example (that usually grows at 37 Celsius) can be greatly slowed down at lower temperatures. Also, there are enzymes involved in the "ageing pathway" some of these enzymes can be promoted or repressed by small molecules, like resveratrol does, and as result you get some increment in life span. The opposite is also true, you can accelerate ageing with external factors. For plants works as well, changing the environment you can definitely have an effect on the life span and the overall metabolism rate, indeed tricking the light cycle is a very well known method to induce flowering for example.

Here some interesting links if you wanna dig more into this topic.
http://web.mit.edu/biology/guarente/
http://genetics.med.harvard.edu/sinclair/
http://www.ted.com/talks/cynthia_kenyon_experiments_that_hint_of_longer_lives?language=en
http://jxb.oxfordjournals.org/content/58/12/3099.full