According to their website you continue using the same Java app: Do I need to install a new CrashPlan app? No. The conversion process automatically updates the CrashPlan app on your computers. Instead of the green-themed CrashPlan for Home branding, you'll see the blue-themed CrashPlan for Small Business branding.

[0] https://support.crashplan.com/Subscriptions/Migrate_your_Cra...