Water in the Crater Lake at White Island has now risen to a depth of about 15 metres.
The lake began refilling last December after almost completely evaporating in October 2007.
GeoNet Duty Volcanologist Steven Sherburn said the lake was now within about nine metres of overflowing.
Changes similar to those seen the last time the lake began refilling in 2004 were being noted, including old springs on the main crater floor flowing again, and new springs forming, Mr Sherburn said.
No significant changes in volcanic activity had been seen on the island, off the Bay of Plenty, and the alert level remained low.