Hmm, 2,5 hours is not much. Not knowing what you have done in the previous 3 days, but you might consider a 1-hour canal-boat trip, price usually around EUR 13,-
On Sunday from 12.00 (noon) the shops are open in the citycentre till about 18.00 hours.
Weahter is quite nice these days in AMS
, so consider a train ride to Zandvoort aan Zee, direct trains from Amsterdam Centraal Station. In Zandvoort walk straight out of the hotel towards the Northsea beach. Find several beachhouses, cafe etc overlooking the beach and enjoy a light meal, a drink or whatever you like.
Calculate about 30 minutes for the trainride. So you have about 90 minutes left to spend in Zandvoort.