Then you perform the experiment exactly* how you said you would based on the pre-registration, and you get to publish your results whether they are positive or negative.
* Changes are allowed, but must be explicitly called out and a valid reason given.
Also, forcing pre-registration on everyone would be problematic because some types of research are not well-suited to strict planning and committee approval -- how would you quickly make adjustments to an experiment? how would you do exploratory data analysis? serendipitous discoveries would be suppressed? etc.
This way, when you find one significant correlation after testing ten thousand options, you have to say you tried all ten thousand, rather than make it sounds like you only tested the one.