Cookies can only store strings. Therefore, you need to convert your array into a JSON string. If you have the JSON library, you can simply use JSON.stringify(data) and store that in the cookie, then use $.parseJSON(data) to un-stringify it.
In the end, your code would look like:
var data = [
{ 'name' : 'Abel', 'age' : 1 },
{ 'name' : 'Bella', 'age' : 2 },
{ 'name' : 'Chad', 'age' : 3 },
];
$.cookie("data", JSON.stringify(data));
// later on if you need to add any element...
var data = $.parseJSON($.cookie("data"));
data.push(
{ 'name' : 'Daniel', 'age' : 4 }
);
$.cookie("data", JSON.stringify(data));