Usually the price will go up after the rebate expires. Sometimes it will not go up as much as the rebate was before hand. I have seen some rebates where they expired and the change in the overall price was not much at all. When I bought my 70-200mm F/2.8L II last year in January, the price expired then they had a price increase immediately after that. I bought mine right before the increase and saved a fair amount. I remember once in a rare instances the rebate started and the price was slightly more with the rebate than it was without, I believe it was the price of a 7D in that instance.

If you want the lens at the price it is now, it would probably be best to buy it while the rebate is on. The 135mm is an older model lens, if I were guessing I would say it will go back up but probably not the full amount of the rebate. But then I would be guessing, the only way to know for sure is if you can get B&H to tell you how they do their pricing structure.