Town officials have begun preparing what is expected to be a lean budget for fiscal 2015. The Board of Selectmen asked all non-school department heads to submit individual budget proposals that keep spending to no more than 2 percent above this year’s levels, according to Joseph R. Pacheco, the board chairman. “To an extent, things have been tight, but we’ve always been conservative in terms of how we run the town,” Pacheco said in an interview, of the board’s decision to seek only a small spending increase. The Bridgewater-Raynham School District is separately preparing a series of options for its budget to present to Raynham officials. The finance committee is set to begin reviewing both the non-school and school budgets at its meeting Monday.