Nope. In fact, your website might move up in the rankings. I've been able to get a particular website of mine to the first page of Google just by updating the homepage article. I woke up the next morning only to find out that the updated article had been indexed and that the homepage had hit the first page for its target keyword.

Sometimes it's not always the case, some little changes like that can bring out disruption to your ranking though if you still have the on page done properly along with quality links you could regain your position sooner than later or even move higher.

But be aware, anything can happen...

It's possible a ranked page is just barely holding rank so an on-page edit could drop the page. Or, changing/updating something like a page title text could even drop a page in the SERPs.

Why not build a 2nd internal page on the same subject as the already ranked page, then use internal links to connect the two pages? That would help strengthen the already ranked page.