You have a few options. Firstly, remember of the quality of training. Find the right e-course provider who will prepare creative and modern solutions for your company. Ensure the quality and attractiveness of courses for your employees and they will ask for more.
Secondly, try out the gamification process. Create a kind of game with the training system in your company, where your employees could gain new points and achieve new levels. They may exchange their points for prizes, e.g. additional vacation days, integration events or extra external trainings.
Last but not least, with your Learning Management System you can create a set of prestigious internal certificates for your employees. The certificates will be automatically generated and downloaded by the trainee after finishing selected trainings.