Dried mint and fresh mint have different jobs
The idea
Fresh mint gives a cool, leafy aroma that is noticeable as you bite. Dried mint can spread a different herbal note through a mixture or dressing. One is not simply a weaker version of the other; the texture and the way the aroma reaches you can change the finished dish.
A practical next step
Use fresh leaves where you want to taste the herb itself. Check a recipe before replacing them with dried mint.