Hi Denise ~ I realize I am late to the party, not sure how you reduced the sodium, this is what I did to reduce the sodium.
There are homemade low sodium ranch dressing mixes online, I make up a big batch and keep it in the fridge. Not difficult to make at all, just takes planning ahead for the ingredients.

I use a turkey gravy mix instead, because you can buy a sodium reduced variety. It will make the sauce thicker, so I add approx. 1/4 cup of low sodium chicken broth so it doesn’t get too thick. We use a no salt margarine all the time, so just add a few tablespoons of that, in place of the butter. It has a high water content, so that will help thin the sauce as well.
If you still want the au jus flavor, try using a low sodium flavoring like OxO, I buy those on a regular basis as well.

We had to go low sodium two years ago, my husband had a mild heart attack, it can be a challenge, but I find pre-planning (Like having ranch mix at the ready) really helps down at mealtime!