You're trying to find a technical solution to a people problem. That generally doesn't work. Finding a people solution will yield better results: stretch targe

You're trying to find a technical solution to a people problem. That generally doesn't work. Finding a people solution will yield better results: stretch targets; output quality reviews; regular 1-2-1s; discussion about career progression; more responsibility. If they're actually at a low enough level where a program will obviate the need for you to fulfil your managerial responsibilities, why not outsource, pay for piece work, etc. There's no benefit to you to keep motivated workers employed - there's nothing to motivate them /with/.