A plan to repair, upgrade and keep the 50-year-old XL Center in downtown Hartford running and relevant will cost $107.2 million. Hartford officials and CRDA staff see the sports and entertainment arena as a key city attraction, something that brings in crowds to patronize local restaurants on event nights and adds to the city’s vibrancy. The aging facility is currently undergoing millions in repairs and will need millions more to keep functioning, even without a dramatic overhaul, said CRDA Executive Director Michael Freimuth. The current plan would keep the building running and make it a more appealing and efficient venue, allowing it to bring in more performances, he said. In addition to rehabbing core systems, like the roof, plumbing, electrical and elevators, the planned rehab would redesign the stage, create premium seating areas at ground level, renovate seating, upgrade vending stations and other functions on the concourse and more.