Is there something I can do to keep ice-cream soft?
Yes, actually, there are two magic ingredients: Guar gum and Xanthan gum.

Guar gum is a thickener, but in small quantities can also prevent the growth of ice crystals which would cause the ice cream to harden into icicles.

Xanthan gum is a stabilizer which helps keep air (called overrun) in the mixture.  Air is generally churned into ice cream by ice cream machines, but it won't stay that way without the stabilizer.