Which monetization strategy to use for In-App purchases

I have a successful alarm clock app which turns an Android device into a professional wake-up light (https://play.google.com/store/apps/details?id=com.changemystyle.gentlewakeup). The app has some nice extra features like weather forecast, power nap and sleep timer. Currently there is a free ad-based version and a pro version.
This monetization strategy was sufficient for the past. But now I will not increase my sales when I develop new features. Therefore I want to change the strategy so that customers need to pay for each function individually and also need to pay for future functions. On the other side I do not want to loose the ranking of the Pro version and the customer self-marketing actions like sharing the app to friends for a free unlock.

My new idea is:

• Each feature works but configuration options are only available by a premium purchase like duration of the sleep timer.
• Each premium features can be tested without any signup for 3 days
• After 3 days the customer needs to make a purchase to unlock configuration options.
• The customer can extends the trial perdiod by 1 week if he is doing some marketing sharing activity.
• Many different purchasing options should be available so the customer can find the one he/she likes best:
  • One-time payment for a feature (6,99 €)
  • One-time payment for all features (39,99 €) but no free future features. The price is lower than buying each feature individually
  • A monthly subscription to get all current features and all future features for 2,99 €.

The pro version now can be:
A: a one-time payment with a very high price (79,99 €) and will include all current features and free future features for lifetime
B: a one-time payment only for all current features but future feature will show a premium note and need a new purchase

With option A I am afraid that the price feels to high for a customer. Also the customer is lost for the future
With option B I am afraid that the customer will be upset when he paid for an app in the play store and he will see a new payment requirement in the future.

I would like to know:

• What is your opinion on these pricing models?
• Is the screenshot (http://download.sabov.de/screenshot.png) of a payment for an in-app feature clearly understandable for a customer?
• The weather forecast costs me money but over the lifetime of a customer it is probably a few euros max. It could be made as a subscription instead of a one-time payment.
• Removing ads could also be made as a subscription because otherwise the customer is lost until there will be a new feature available.