Routing in polymer 1.0

I am new to web development and building an application using polymer 1.0.4. I am using the page.js routing similar to the example in start kit. Now many of the custom element that I built are using ajax and periodically refresh the data. The problem with page.js routing that It seems it loads all custom elements even if the element is not viewed by user. so all custom elements are loading the data even if it is not needed. my questions:

1- How could I fix this so the the elements load data only when they are viewed by the end users? Should I change the routing to another options like more-routing?

2- if the user filled the data in one custom element , then clicked on link to another element. The data will remains when the user goes back to the first custom element? How could I reset the polymer and html elements in the custom element when the use back to an old view?