L1B Blanket Visa

Dear All Your contributions to this forum have been very helpful and I can finally see some hope in my case. I have explained my situation below, I really hope you can give me an answer too. My wife and I arrived in the US on my L1B Blanket visa (My wife on L2) in 2013. Both our visas are valid till 2018. Since L1B visa is stamped on 3 + 2 years basis, our current I94 is valid till 2016. Both our passports are valid till 2022. Most cases discussed in this forum had to renew because current I94 was stamped as per passport validity. My case is different hence I need your help/suggestions. Can my wife and I still go to Mexico border and ask CBP officer to extend our I94 till the end of our visa validity i.e. 2018? If yes, please advise if there is any recommended time period to make this trip before our I94 expires (1 month, 2 months or 3 months)? What specific documents do I need to carry for both me and my wife? Also, one of my colleagues (L1A visa and dependents on L2) recently made a trip to India with his family. On their return, their I94's were automatically renewed for additional 2 years by the CBP officer. Is this another option? Will it work for me If I am on L1B? Eagerly awaiting your helpful responses.