I know the first rank in bf you can get is with 150 points. so I search for 150 in several files and test it then.
You must change the value for the ranks in each file above and exactly like you've done it in the file before!!! I think the best way to do this is to look how many ranks there are and how many points you must have to get the new rank. then you think about how good your players are and set the points for the new rank. (like me in a excelfile: imglink)