There is not - this is the biggest deficiency of Hedgehog today. Without centralized custody of keys, it's not possible to have someone prove their ownership of a given key to a centralized party in order to unlock it. The key is encrypted, so the application provider nor anyone else can decrypt it without the user's username/password combination. This tradeoff is both a good thing and a bad thing in our view.
That said, there is a mechanism for changing your password if you are already signed in.
We are considering some mechanisms for fallbacks, eg using a threshold cryptosystem with multiple private keys and a 1 or 2 of n requirement, such that if a user forgets the way to generate one of the n keys they may still remember a way to generate the other(s). If you're curious, more on these schemes here: https://en.wikipedia.org/wiki/Threshold_cryptosystem
We feel these tradeoffs make sense to enable more mainstream adoption of cryptocurrencies, but they are tradeoffs; for certain types of applications the cost of losing control of an account is too high for this approach to make sense.
