I'm not disagreeing that reproducibility is a problem. Of course it is.

I'm asking how to fix it. How do we incentivise reproducibility?

You have to fund it, simple as that. Tenure is granted to professors who get grants. Grants are gotten by publishing papers. Papers are published by conducting novel research.

One thing we could do is mandate that some portion of all grant money has to be given to independent researchers who will work to confirm your findings. I could imagine some downsides to doing this, but at least it would put money in play.

Also, another problem is that the people doing research are usually grad students working toward a Ph.D.. No one wants to do a Ph.D. confirming someone else's results. You'd need some other workforce to do the work of reproducing research. Again, doable but there needs to be money allocated for this task.