Is there a way I can "find and replace" text inside equations? 

e.g.: I need to replace all $\hat v$ by $v$. 

Since [MathJax](https://math.meta.stackexchange.com/questions/5020/mathjax-basic-tutorial-and-quick-reference?lq=1) doesn't work here: Replace a "**v** with a **^** on top" by a "**v**".