I know that After Effects has a "bullet time" effect where you can slow down a sequence without it becoming jerky by creating the intermediate frames necessary. I'm looking for that technology, but simpler than After Effects, where I can give it, say, a 15 minute video that was shot at 30fps and after 8 hours or so, get a video that was effectively shot at 60 or 120fps. The software would extrapolate between frames and add two or three intermediate frames after each original frame.
My understanding is that you either want to stretch the time of your footage, or effectively double its frame rate. You can use AE's time-warp or time-remapping feature and play around with things like frame averaging. So you could timestretch the layer, then add timewarp the same amount.