(AP) – Shoppers have been seeing signs of an improving economy — enough so that they picked up their spending in April from March despite cold weather that stopped them from buying spring clothes. According to a preliminary tally of 11 retailers by the International Council of Shopping Centers, revenue at stores open at least a year rose 3.4 percent in April from last year. That’s up from a 2.2 percent gain in March but still shows modest growth.