Should You Plan for Your Next Incarnation?

Yes, although, with respect to the bit I've bolded: perhaps we could distinguish between challenges/problems/evils due to natural errors and those due to free will choices. It seems that those due to free will choices are unavoidable (by the designer of the system, assuming S/He/They respects free will highly), but with respect to natural ones... is this really the case? We know that it is possible for Him/Her/Them to miraculously heal cancer, so it would seem that this type of error/problem is fixable and thus avoidable. We still, then, don't understand why some souls are forced to live lives of nature-based suffering.

I agree re. the evils that inevitably result from the necessity of free will.
 
With regard to "natural evil":

The following is sort of an apologia that makes a case. But it is a case that I think is inherently questionable because of the vast and appalling human suffering that exists - this terrible price sometimes seems just too high for the benefits of Earth existence. Of course this is the human personality perspective, not the soul's.

There is the observed regularity of natural law. The basic laws of physics appear to be cleverly designed to create conditions suitable for human life and development. It can be surmised that this intricate fine-tuned design is inherently a series of tradeoffs and balances, allowing and fostering human existence but also inevitably allowing "natural evil" to regularly occur. In other words, the best solution to the overall "system requirements" (which include furnishing manifold opportunities for humans to experience and achieve) may inherently include natural effects that inevitably cause suffering to human beings.

This points out that there may be logical and fundamental limitations to the creativity of God (or whatever other supreme Agent or Agents are responsible for physical reality). Maybe even He or They can't 100% satisfy all the requirements simultaneously. Maybe He doesn't have complete control over nature, because that would interfere with the essential requirements for creative and fulfilling human life. After all, human achievement requires imperfection and adverse conditions to exist as a natural part of human life.

So: what if there were no limitations and by Divine command all "natural evils" like disease, earthquakes, forest fires, etc. were miraculously prevented. This would drastically reduce human suffering, but the tradeoff would be that a large part of our human drama would be turned into a divine puppet show, and by subverting the operation of natural law it would cost us one of our greatest blessings: the regularity of natural law which makes many of our achievements meaningful and science a great and beneficial enterprise.

Maybe there is a lot of truth to the old saying "life is a series of tradeoffs".