You say you wanted a 5 day pass but as was explained, trading requires ending up with a 7 day pass. This means having 2 days left over. (You also end up with 2 more plusses than you had on the old pass)
Since your trade up outlay was $147 per person for three more days, the cost per day is $49. so you will have two leftover days that cost you $49. each.
Something to be aware of: It is difficult to use up two leftover days during a longer vacation and get good bang for the buck.
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One of the countless alternatives.
Trade up to a ten day pass rather than a seven day pass. The outlay is $206. rather than $147, or $41. per day including the day you used now. You will have five days left over rather than two. For many folks this perhaps together with Universal Studios will be enough for a complete second vacation further in the future without the need for another trade up.
Another alternative.
If you can confine your theme park activities to four days and use the plusses for the remaining day of your vacation, you don't have to do any trade up and your outlay is zero dollars. (Requires separate admission of $35. if you want to go to Disney Quest, or is even less flexible if your vacation was really 6 days and you already planned one of them as plus-only.)
Another alternative, I don't like this one.
Use the old pass as-is and buy a new one day pass for the last day. Outlay is a minimum of $64. No park days are left over. But notice that the cost of the fifth theme park day is $64 non-hopping, not $47 with hopping. Also does not include Disney Quest.
Hint: If you use more of the plusses on the old pass before trading, you do not diminish the trade up value.
Disney hints:
http://members.aol.com/ajaynejr/dispass.htm