Pardot's proprietary Site Search functionality will be removed as a feature soon. Please replace your existing Pardot site searches with third-party site searches.
Pardot can integrate with your third-party site search and provide reporting on their queries. Nothing shows a prospect's intent like his searches on your website. If someone clicks around and finds their way to your pricing information, that is valuable to know, but if the prospect types in "pricing" as his exact search term, that is a much better buying signal.
See this article to set up a third-party site search. If you want to set up a Google Custom Search, see this article.
Clicking on a specific site search in the table at Marketing > Site Search will give you more information about the search. Here, you can view configuration details, and search query information (the query, prospect name or visitor ID, and timestamp). From here, you can easily access detailed site search reports -- click the View report link at the top of the page. You can also access your Site Search Report by navigating to Reports > Site Search.
Be sure to check out our other site search articles for more information:
Integrating Third-party Search
Integrating Google Site Search
Site Search Report Overview