Reflationary is the adjective: it describes a plan, a tax cut, a rate cut, a budget that is meant to increase the amount of money at work in a country so that trade grows. People say 'a reflationary package' or 'reflationary measures.' It lives in the same formal family as inflationary and deflationary, and you almost always put it in front of a policy word, not on its own. Though actually, politicians love the label because it sounds like help; whether a given tax cut really does that job is another question, and newspapers argue about it.