Entity framework reload entity from context

I have the following scenario:

I am using EF with Repository pattern and Unit Of Work from here

Then I extended my partial class and have created a Finder class which have GetAll and other methods. You can this see below:

Below you can see that I am using a unit of work class with repositories of all classes to get the instance from the generic repository:

protected Repository<Category> _CategoryRepository;
public Repository<Category> CategoryRepository
{
    get { return _CategoryRepository ?? (_CategoryRepository = new Repository<Category>(context)); }
}

So in this way I had different repositories and when getting an entity from db and updating it from a different context caused problems. So I used this method to use for context lifetime management. And it resolved that issue.

Now the problem I am facing is in the following code:

var cat = Instance.Category.GetSingle(c => c.CategoryID == 7);

var orignal = cat.CategoryName;

var expected = cat.CategoryName + " Test Catg Update";

cat.CategoryName = expected;

cat.Update(); //This doesn't actually update due to a validation in place (which is correct)

cat = Instance.Category.GetSingle(c => c.CategoryID == 7);

Assert.AreEqual(cat.CategoryName, expected);

When I use Update and I have some validators in it, and the Update fails (for example due to size of the string exceeds 15 characters). When I try to call GetSingle (2nd last line of above code) again, it brings me the same old record which is [cat.CategoryName + " Test Catg Update"]. Is this a normal way? If not how can this be fixed so I can reload the object from database.

Let me know if you need any other code or reference.