ameliorating(prenominal), ameliorative, amelioratory, meliorative

from The Collaborative International Dictionary of English v.0.48

bettering \bettering\ adj.
   changing for the better; -- antonym of {worsening}. [Narrower
   terms: {ameliorating(prenominal), ameliorative, amelioratory,
   meliorative}]
   [WordNet 1.5]