the meaning of 참
In the topik test, there's a sentence like this.
남자:좋은 생각이세요.자기 통장이 생기면 돈을 모으는 즐거움을 느낄 수
있을 거예요.참,아이 도장은 가져오셨죠?

I'm asking the 참's meaning here. Is that kind of like 'so~' or 'then'?

Question

the meaning of 참
In the topik test, there's a sentence like this. 
남자:좋은 생각이세요.자기 통장이 생기면 돈을 모으는 즐거움을 느낄 수
있을 거예요.참,아이 도장은 가져오셨죠?

I'm asking the 참's meaning here. Is that kind of like 'so~' or 'then'?

Answer

When 참 means "so" or "very", it usually comes before an adjective or adverb or verb with such a meaning (참 잘한다,  참 좋다).

If it's used independently as in your example, it is an interjection to the effect of "Oh! I just remembered" that you utter when you suddenly remembered something or when you need to switch to a new subject.  In your example, it is a little like "by the way".  It is a different usage unrelated to "so" or "very".