Did you compare the data the release was based on versus the numbers you imputed to get your numbers? Was there a change in runways, runway condition, temperature or wind? Did your numbers tell you what the limiting factor was, runway or climb performance? Did you call your dispatcher and ask about the difference?
121.195 says you can not depart to an airport unless at the planned landing weight you are able to stop within 60% of the landing distance available (not add 60%.) To make the math easy, if the performance date says you need 6000 feet to land, the runway you plan to land on must be 10,000 feet. Once you takeoff that goes out the window. Say your destination airport has two parallel runways, 10,000 and 7500 feet long. You can land on the shorter runway because you only need 6000 feet to stop. If you have an issue enroute and your procedure requires you to add a performance penalty you would add it to the 6000 landing distance.
As pointed out above your QRH should have some performance in flight tables to get an idea what your landing distance will be. And some airlines use an onboard computer to figure performance so it doesn't matter if ACARS is inop.
The FAA has been pushing manufacturers and airlines to use factored landing data which has an additional 15% added. So if the manufacturer determined that your aircraft with a given set of conditions needed 5000 feet to come to a stop the tables would say you 5750 to come to a stop.