My fiancé and I have been engaged 1.5 years. Do we still have an engagement party and what all do we plan for that?

In your case, since you have been engaged for a year and a half, probably your families already know each other and perhaps you have already discussed the wedding finances, or it isn't an issue. Engagement parties are generally to announce your engagement to your family and friends and provide an opportunity for them to better get to know each other. So, it's really up to you if you want a formal engagement party or not. You don't have to have one, but it's always a good reason for families to get together and socialize with each other. And since it's probably not for introductions of the two families, it may be a good time to go over your plans and details of the wedding when both sets of parents etc. are together.