I self-insure, so I'm not an expert on this, but it sounds like you want "Cancel for any reason" (CFAR) travel insurance. If you do a Google search, you can find several companies offering this as an extra-cost option specifically for the circumstances that you mention. As usual, be sure to fully read the terms and conditions of the insurance, and be aware that you might not get back 100% of your sunk (pre-paid) travel costs.

That said, I agree with lhrsfo: If your company approves your leave and later renegs, your company should be on the hook for any liabilities. If you change your employment, of course, that's something that you have control over.

Nevertheless, I hope that others will have personal experience about how well CFAR travel insurance works.