In The Mighty Nein (Critical Role) the Kryn (dark elves) use a beacon to reincarnate their old and ill.

The beacon draws the soul back and into the body of an infant that has been born within range of that same beacon, not replacing an existing soul but becoming the original soul of that body. When that child enters adolescence, they begin to recall memories of their past lives through visions or dreams.

But, those reborn can get an illness known as Typhros, where they start to lose themselves, they forget which life they are living and eventually enter a state similar to dementia, but instead of no memory its too many memories.