Change of status from L1 Blanket to L1 Individual


I am currently staying on I-94 and my I-94 validity till Jan 2015. My L1B visa got expired in the year 2012. Since there are many L1B visa extension rejections, I wanted to do change the status from L1 Blanket visa to L1 Individual visa.

I would like to ask question will it be possible to change of status from L1 Blanket to L1 Individual? What is the success rate for L1 Individual visa extension?

If it is possible, how many days before I request my comany to initiate the visa renew process?