Should I get a new dress?

So my brother is getting married in months. Only found out and it’s a destination wedding. I have a dress his fiancé (not sure if the spelled right) said would work. I do t want to spend more than j need to. As is I have to pay my son an outfit and his going to be the ring bearer (which I’m happy about). My husband has something that will work. It’s is the dress I have. I have wear it for a lot of things at this point. Got it for a friends wedding two years ago. Have wear it at least 15 times. I love the dress but should I get a new dress for my brothers wedding? I’m just not sure how I feel about it and if it’s something that should really be done.