The difficulty right now doesn't bother me. I think more item drops from monsters or finds would be better than lowering the difficulty.
I don't think people will be willing to pay $0.99 for every continue, especially if the die twice in one run (that would frustrate me). But, permanent unlocks are definitely a plus like: starting at level two, unlocking a specific spell, item, or weapon that could be used at the beginning of each run.
There's also the possibility of leaving the characters items behind from the last run as a possible loot, like in Dark Souls games.
There are two games that I have seen apply the Fallout percentages aspect (i.e. accuracy and damage differing against upper, mid, lower or specific body parts). I've always found that fascinating.
I don't know if you've played Buriedbournes, but I think a lot of what that game has can be learned from for these types of Roguelite RPG's. I mainly don't play that game because of the crude graphics; which your game has eliminated. Since you're wrapping up the game for the Android release, it makes my suggestions a bit difficult because many could require a bit or coding (which I know nothing about) or change that you may not want. It depends if you view this game as a living model that you will continue to update and grow, or if you just plan to put it out there and let it be.
Also, I did notice some grammar and clarity errors in the writing. If you are interested, I would be willing to go over your text to clean it up as I am starting a freelance proofreading/editing portfolio, and I have an English degree. Either way, I thought I'd make the offer. Thanks for getting back to me.