Loading more items for an activity feed that uses a global page counter
This doesn't have anything to do with ajax or the options exactly, just about "counting up" so i will show my example using a function called countUp which logs ever increasing numbers.

In short you can make page a member of countUp. You will recall that in javascript that functions are very much first class citizens and they are objects. Its easier to see this of course if you write your function definitions like:

var countUp = function () { /* .. function body */ }


So the variable countUp can have in it any number of members. The member we are interested in is page or more precisely this.page. So lets put this all together.

var countUp = function ()
{
    this.page = (typeof this.page !== "undefined") ? this.page : 0;
    this.page++;
    console.log(this.page);
}

countUp();
countUp();
countUp();
// logs 1 2 3