Use a new context. The cached entities are stored in the context. Using a new context prevents it from using the cache.
If you really want a global/long lasting context, you have two sub options:
a.) always call the Reload method. db.Entry(entity).Reload() ... this forces the context to reload that entity.
b.) use a SqlDependency object to detect when records change and reload the entities as needed. https://code.msdn.microsoft.com/How-to-use-SqlDependency-5c0da0b3