arterial blood clots in my groin

I am 46yrs old and in 2005 i had a blood blot in my right groin, a stent was placed in my artery. then again in 2006 another blood clot was discovered in my right groin. another stent was placed. Recently another clot was detected in my right groin, they did angiogram and found another blood clot inside my stent about 4 inches long. what can be done now to fix the problem?