Wordpress widget adding variables

I want to add a filter feature to my wordpress widget. For this, I must be able to add as many filters i want. For its implementation, I am adding filter select box and text box to accept filter value, on the fly through javascript.

My problem is;

1. How can i save these values to widget instance variable. So the next time they should be visible.
2. How will I开发者_运维问答 access these values for processing.

Please let me know if I am not clear on some point.