EACH YEAR THE CITY SENDS ROUGHLY 1,200 juvenile lawbreakers to jail-like facilities in upstate New York. At an average annual cost to the city totaling well over $100 million, some of the youth are placed in institutions run by the state's Office of Children and Family Services (OCFS) and others go to privately operated facilities under contract with OCFS. But two new programs with an alternative approach are now saving the city considerable expense and may prove to be more effective at rehabilitation than the institutional approach.