Below I say that the mod is version independant and works with every Minecraft version 1.5 and up. This is true in general, but the new launcher broke the mod.
In Minecraft 1.5 the statistics system has changed and the resetting of statistics should be rare to impossible. If you want you can still use this mod, but it's way less important than before 1.5.
This mod removes the resetting of statistics and achievements.
Additionally it will make the game access the statistics file stat_keepmystats_unsent.dat (instead of stat_<username>_unsent.dat). So when you start the game without the mod installed, it won't mess up your statistics.
The mod is a FML coremod. This means it requires FML or Forge and goes into the coremods folder. It does not do any Minecraft stuff, so it should be independent of the Minecraft version. It should work with all future releases and snapshots that FML works with. You can even put it in an MCP installation in the coremods folder.
Statistics are client only. Don't install the mod on a server.
Download + Installation:
Copyright + Modpacks: