I have had dermatographic urticaria for over a year, when will it go away ?

Dermatographism: Isn't uncommon, usually in young adults as yourself, a form of physical urticaria,usually doesn't need treatment,but if your symptoms are bothersome you can ask to see a dermatologist/allergist to evaluate your condition.Usually no cause is found,simple skin care can help,cure takes time,check this link for more info http://www.mayoclinic.org/diseases-conditions/dermatographia/basics/definition

No way to know: Since dermographism falls under the label of "physical urticarias" avoiding triggers is key. Heat, vibration, pressure and cold can trigger both local and generalized skin reactions. Sometimes autoimmune disorders such as hypothyroidism can be associated. There are current standards of care including higher doses of 2nd generation antihistamine like zyrtec, xyzal etc.