Either find time and give the v2 a try or shut it down. it is that simple. Just make a decision. Nobody can make this decision for you.
I would try to sell it only if there is something to sell, otherwise it will be waste of time. Do you have significant userbase, some interesting data, and etc? If yes, poke your competitors first.
Could you not just abandon it and leave it on the app store? Obviously, leave caveat on the app description that this app is abandon and no support will be provided. In this manner, at least if someone wants to use it, they can.
