How to replace an Paragraph's text using OpenXML Sdk

Fixed it myself. The key was to remove all the runs and create new runs in the current paragraph

string modifiedString = Regex.Replace(currentParagraph.InnerText, currentString, reusableContentString);
currentParagraph.RemoveAllChildren<Run>();
currentParagraph.AppendChild<Run>(new Run(new Text(modifiedString)));