Recent approaches in testing autonomous driving systems (ADS) are able to generate a scenario in which the autonomous car collides , and a different ADS configuration that avoids the collision. However, such test information is too low level to be used by engineers to improve the ADS. In this paper, we consider a path planner component provided by our industry partner, that can be configured through some weights. We propose a technique to automatically re-engineer the path planner in terms of a self-adaptive path planner (SAPP) following the MAPE loop reference architecture. The Knowledge Base (KB) of SAPP contains descriptions of collision scenarios discovered with testing, and the corresponding alternative weights that avoid the collisions. We forecast two main usages of SAPP. First of all, designers are provided with a prototype that should facilitate the re-implementation of the path planner. As second usage, SAPP can be useful for improving the diversity of testing, as performing test case generation on SAPP will guarantee to find dangerous situations different from those used to build SAPP. Preliminary experiments indicate that SAPP can effectively adapt on the base of the solutions stored in KB.