What's left? Aside from negative interest rates to drive people to either spend, or start hoarding cash in mattress. There could be a moratorium on corporate taxes to try and increase spending that way, but corporations would likely just use any cash to buy back shares, which they did a lot of during the last recession, and they leveraged up to do it too.
And would drive up the deficit even more as well. How long can we support $2 trillion or $3 trillion deficits?