Inventors are typically overworked and underpaid. They do their job because they love the work. Encouraging inventors to be more creative or spend more time on patent protection paperwork can be difficult. I mean, who WANTS to talk to a patent attorney? Fortunately, time and money do not drive most inventors.
What inventors really desire is recognition of their creative efforts and their contributions to the company. Instead of cash or time off, try engraved patent plaques to hang on their walls or discounts on company products. Having something tangible recognizing their contribution is far more satisfying than money for most inventors. Be creative. Look at what non-monetary recognition your company may have to offer. A little thinking can increase your R&D output while at the same time making your inventors much happier.