It's very difficult to arrange so that change in values is good. I expect you'd need oversight from a singleton for that to become possible (and in that case, "changing values" won't adequately describe what happens, as there are probably better stuff to make than different-valued agents).

We do seem to have an example of systematic positive change in values - the history of the last thousand years. No doubt some will argue that our values only look "good" because they are closest to our current values - but I don't think that is true. Another possible explanation is that material wealth lets us show off our more positive values more frequently. That's a harder charge to defend against, but wealth-driven value changes are surely still value changes.

Systematic, positive changes in values tend to suggest a bright future. Go, cultural evolution!