I wish to do interlinking within wordpress pages and say my URL is www.test.com for instance and that i have www.test.com/p1 www.test.com/p2 and www.test.com/p3 pages and I wish to add p1 and p2 links in p3 from admin side.. at this time, I simply place and same for p2.. but when my permanlink changes than i have to change content again.. Can there be any means to fix this.. in order to in a position to place just ID of page with and it'll convert it instantly to link.

You should use the shortcode api to create links with publish-ids. Whenever you add following code to your function.php

add_shortcode('permalink', 'permlink_replace_func');

function permlink_replace_func($atts){

    extract(shortcode_atts(array(
        'id' => '',
        'lable' => 'link'
    ), $atts));

    $permpost = get_post($id);
    $html = '<a href="'.get_permalink($id).'" >';

    if ($lable==null) {
        $html .= $permpost->post_title;
    } else {
        $html .= $lable;
    }

    $html .= '</a>';

    return $html; 
 }

you are able to enter a string like [permalink id ="8" lable="hallo world"] within the content section of a publish to obtain a connect to another publish per id.

More details about shortcodes you'll find in the WordPress Shortcode API.