Reset Keys

Option for Longtime Minecraft worlds: Reset Nether & End for new generations; Reload / Reset unused chunks - to ensure new world generation as well as cut back on the size of the world due to unused traveled space. There have been similar keys with the older console editions of Minecraft (specifically for the Nether and the End). A lot of folks including myself have worlds that date back by 5 updates at least and want to continue playing on them. While we would like to have the ability to have access to the new content the issue is sizing due to players that travel out 10,000+ blocks at every direction, pushing the biome generations out farther. As a result the size of the world increases tremendously making it harder to run feasibly. I can understand the reasons why a button like this cannot exist but if it the option is there and it is indeed possible, then please give us this extra tool.