No. EPA has not discontinued monitoring of any type of radioactive particle. EPA maintains a routine sample and analysis program for beta particles for each RadNet monitor location. You can download the beta particle results from the laboratory at: http://ofmpub.epa.gov/enviro/erams_query_v2.simple_query
In the past, EPA attempted to supplement this laboratory analysis by adding near real time beta detectors to the RadNet monitors. EPA has discontinued this because the detectors were not able to confirm or rule-out the presence of beta emitters, did not provide identification or quantification of specific nuclides, were subject to various interferences, and did not provide actionable information to EPA scientists.