Home improvement chains, discount stores and other types of retailers are filling up their shopping carts with new sponsorships.   The category’s eight biggest players spent an estimated $245 million on sponsorship in 2014, up from roughly $220 million in the previous year, according to IEG research.Four companies increased their sponsorship spend from 2013 to 2014: Lowe’s Cos., Bass Pro Shops, Macy’s, Inc. and The Kroger Co. Home Depot, Aaron’s and Menards kept...