What is a good pattern for combined caching and reinitialization?

Question

I have a situation where I have three requirements:

1. Lazy initialization - don't create the collection until asked for it
2. Caching - keep the collection in memory on the object
3. Reinitialization - be able to reinitialize the collection when desired, instead of simply getting the existing results.

This is simply an optimization inside a single class - it is not loading anything from a database and ideally I'd like just a good method design pattern for this, not a multiple-class design.

Usually for lazy initialization I'd have this:

Collection getCollection() {
    if (collection != null) {
         // generate and set collection
    }
    return collection;
}

But now I'm having trouble deciding on the best way to provide for reinitialization of a fresh collection and getting that collection. A fresh boolean parameter would work, but adding a parameter to a getter doesn't seem to feel right (maybe that's the Java in me talking — I could be convinced).