Here's another review on the topic.
Points of interest:
Although thrombophilia testing predicts initial VTE it is not reliable for predicting recurrance.
Thrombophilia testing does not have a primary role in decision making regarding the duration of anticoagulation.
Thrombophilia testing has a limited role in individual circumstances and must take into account patient preference.
D-dimer testing after a course of anticoagulation is predictive of recurrent VTE and has a role in decision making about the duration of anticoagulation.
The duration of anticoagulation is largely a clinical decision, based on current guidelines and modified by the clinician's judgment in individual circumstances and the preference of an informed patient.
The recommendations in this review are similar to those of another review I linked here.