Neb. Rev. Stat. §§ 18-1908
All original and renewal licenses may be renewed by the plumbing board at the dates of their expiration. Such renewal licenses shall be granted, without a reexamination, upon the written application of the licensee filed with the plumbing board and showing that his or her purposes and condition remain unchanged and that he or she has complied with all other applicable rules and regulations required by the city council or village board of trustees. If it is made to appear by affidavit before the plumbing board that the applicant is no longer competent or entitled to such renewal license, then the renewal license shall not be granted until the applicant has undergone the examination required pursuant to sections 18-1901 to 18-1913.
Neb. Rev. Stat. §§ 18-1908