I did go there just before the war,but I have't gone there since.

原意是：我确实在战前去过那里
如果换成你的，就变成：我曾经在战前去过那里，而且似乎应该用i had been there。

把did go there 换成have been there。

I have been there before, but i haven't gone there since.

did go there,应该是有强调含义的，最好不要替换

had gone 的意思 是 去了 没回来
did go there 是去过，但是回来了。
I did go there just before the war,but I have't gone there since.
的意思是说：在战争爆发之前我去过那，不过自那以后就没去过（去了没回来 ）。