how to load add-in again n again?

Question

I have one qus.
i created one shared add-in in c#.net.
This add-in is working fine.
now i want this add-in is load again n again when any office application is opened.
For e.g. when i open any MS word document then add-in is load for that and if after that i opened another MS word document without closing previously opened document then add-in is again load for newly opend MS word document.
But when i opened MS word at first time the add-in is load and if i opened MS word again but add-in is already loaded.