In CC the best way to scale up is to use the new Effect>Distort>Content Preserving Upscale by applying that effect to your video layer.
If you have another version of AE there are 3rd party solutions that are quite good.
Or, you could drop your video in Photoshop and resize it and render out an image sequence or a production codec copy there.
Here is detail about the bicubic sampling option added in After Effects CC (12.0):
As Rick says, you can get even better results for many videos (though at the expense of longer processing time) using the new Detail-Preserving Upscale effect added in After Effects CC (12.1):