Restoring US Currency Option?

I did a quick search and didn't find anything.

I was only planning to acceot CAD payments, so I took off the US option. But now I want to have both.
Anyone know how I can restore it without losing any other customizations I've made? Thanks!

You can configure your store's currencies in Admin->Localization->Currencies

But if I do it that way I have to manually update the exchange rate when it changes.

Isn't there a way to have it update automatically?

You always have to manage the exchange rate yourself.

There are some addons available to handle some degree of automation if you have the technical skill to implement them and the required hosting account permissions to do so ... but the fact remains that you must manage exchange rates yourself, and even if you do automate them to some degree, you should always be reviewing them for accuracy.