export animation only to UE4?

Hey, so i was making a game in Unreal Engine 4 and i have a character in that Engine with a load of animation and scripts and stuff, but now i remmember that there is a very importaint animation that i need that i forgot to animate befour i imported it to unreal Engine. So now i need to import a new animation. but how?..

All i can do is to export the model as FBX once again, but that will make unreal Engine 4 import the model again, witch leads to a dublicated model with Another armature

You just need to select the armature and export it with only selected checked in the exporter. Then in UE4 select the already existing skeleton.