Check with Dell service manuals whether there are other configurations for your laptop with higher-resolution screens. You might be able to change the LCD screen with better one, but it will cost you at least $150 for that.
I have looked around for some info,If your resolution size says native resolution.
Native resolution (1366 x 768) seems to be the highest setting you can most likely go with this laptop.I am not saying it is not possible to go higher you probably can.If there is an option on the back for an extra added monitor then i would do it that way.Some of these monitor have there own max Native resolution setting.And so to go beyond it best idea here is to buy another bigger screen that can go beyond it max Native resolution.
It is best to stay at Native resolution until you can figure out how to go beyond it's max.But in my opinion with laptops.Going beyond it's Native resolution can mess with your eyes.