Capcom Unity has word that Lost Planet 3 will be updated tomorrow to complete the game's migration to Steam for multiplayer after Glu killed GameSpy support. They offer complete instructions for PS3 users on how to import their save data to the Steam cloud, and the following word for PC users, including how the leaderboards will be reset:

As previously mentioned, the migration of the online service for Lost Planet 3 (PC Version) is nearing completion, and a downloadable update is scheduled to go live on STEAM this Thursday, July 10th at 1:00am PT. The migration to a new server will unfortunately reset MULTIPLAYER leaderboards and the CINEMATIC GALLERY. CAMPAIGN difficulty will also default to Normal difficulty.

Please note that Item Sphere related achievements for which the unlock conditions have already been met in the current save data, will be unlocked upon importing the save data to Steam Cloud and accessing the Item Sphere. Campaign related achievements, including those related to difficulty will need to be acquired by replaying through the campaign. We apologize for any inconvenience.