I found out now that regenerating lots will in some cases create different landscapes and biomes. While the general coastlines, rivers etc will stay the same, expect some half-mountains, biome breaks and other oddities. It is not as bad as it was in the old days where mountains would start rising in the middle of an ocean, but still quite visible at instances. Unfortunately there is not a lot I can do about that.
The only good thing is that it will not start snowing in places where the lot was not reset.