The next gen Prius needs to come out, that is where Toyota's hybrid technology is refreshed first. Rumours are that the normal 10% improvement should be maintained with each generation, possibly only with lithium ion batteries which may be an expensive option. Plug-in isn't going to be standard, it will be optional as it currently is however it will have more range.
CT isn't going to be refreshed for another couple of years, it has only just had a mid-cycle refresh and needs the Toyota base platform upgrade first, be that the modular platform the new Prius will be built on or kept as a rebadged Arius.