New York University has prevailed in a lawsuit that accused it of failing to properly oversee employee retirement plans and causing thousands of workers to pay millions of dollars in excess fees.  In a decision issued on Tuesday, Judge Katherine B. Forrest of Federal District Court in Manhattan found that the plaintiffs had failed to prove that they suffered any losses or that N.Y.U. acted imprudently. While Judge Forrest ruled in favor of N.Y.U. on all claims, she did find “deficiencies” in the processes used by the university’s retirement plan committee.