You don't have any choice of the interpolation algorithm used in AE, so the only thing you can do is unsharp mask / sharpen it afterwards (which I find really ugly).
If you take it into Nuke, Shake, Fusion, then you'll have the usual choice of filters:
box, sinc, lanczos, mitchell, gaussian etc.
Personally, I prefer the soft look to the sharpened variety anyway. I can spot digital sharpening a mile off with my good eye closed. And it looks cheap.