First I am sorry to hear about what happened to your phone. However, I think the tracker will be lost during the process if he tries to reset to factory settings together with all the other files you have. The only thing you can do is to report it lost with your network carrier so they can block it for you.

My samsung phone (model s5350) was stolen in a bus I was travelling, my phone was locked with security password and also the tracker was enabled. The person who stole my phone is definitely trying to crack the password, if he force to unlock by erasing or reinstalling, will the tracker still work or not??