CEDAR RAPIDS — If another try for a casino in Iowa’s second-largest city is to be in the cards again, local officials first must decide when to ask Linn County voters to renew their permission to allow gambling.Local officials told The Gazette they again are contemplating when to hold a vote on the gambling referendum, which Linn County voters overwhelmingly supported in 2013, to keep it alive before it expires this year.It would be a critical vote for the area’s casino prospects — approval of the measure on a second-consecutive attempt would permanently authorize licensed gambling within the county.