low resolution on external monitor for Latitude 6540

Hello, 

I have Latitude 6540 connected to Dell U2713HM  with a DVI cable through a docking station.

The highest available resolution is 1900X1080. Is it possible to increase resolution to the maximal 2500X1440 that the monitor is capable of? 

I read that it might be possible with a displayport cable. There is no dp port on the laptop, but there is a dp port on the dock. Would that or anything else work?

Thanks,

Mike