NEW HAVEN, Conn.--Yale University is intensifying its lobbying effort against Reagan administration proposals for further cuts in funds for student aid and other educational subsidies.

Yale will soon write to thousands of parents whose children depend on financial aid, describing the latest Reagan proposals and the cuts passed over the summer. Lindsey Kiang, general counsel and director of federal relations, said this week.

Last semester, Yale hired former congressman Robert Giaimo as a part-time Washington advisor, and also formed the corporation advisory committee on federal relations. The committee includes Giaimo, former President Gerald Ford, former Secretary of State Cyrus Vance, and former Senator Abraham Ribicoff.

Kiang said Yale--in collaboration with other colleges, students and parents--was successful in reducing the magnitude of the first round of Reagan budget cuts in the spring and summer, but that "just when people thought the battle was over they find they'll have to bear up and fight again."