The Gainesville City Board of Education faces stiff challenges as it puts together its 2013-14 budget. At a work session Monday night, Chief Financial Officer Janet L. Allison said that while the system could end this fiscal year with a fund balance of $6 million to $6.5 million, it also likely will have to deal with some financial hurdles. The district’s teacher retirement and health and other insurance costs are expected to rise by about $1 million, she said.