A part of page stays in memory when you go back. How can I free resources from that old instance of page?

Question

I'm developing an app on Universal Windows Platform. I've noticed that after a few minutes of navigating between pages, my app crashes on low memory devices.

I've tried using Diagnostic tools of VS2015, and here's what I found:

Each time I go from SectionPage to ItemPage and then go back to SectionPage , some small (~10 MB) object of that ItemPage remains in the memory.

This is the first time I went from SectionPage to ItemPage :

(There's one instance of ItemPage )

Then I went back to SectionPage and then opened that same ItemPage :

(Now there's two instances of ItemPage in memory)

Then I repeated it again:

... And the sixth time:

As you can see, those old instances of ItemPage are still in memory.

It seems that this is slowly increasing memory usage of my app, and after a while, it causes the app to crash.

So my question is, how can I release the memory related to that old ItemPage objects?