Conwy council's cabinet met to discuss the matter in private on Tuesday.
A £750,000 project to renew the bridge linking the town with Llandudno Junction started in April and was originally due to last 20 weeks.
However, corrosion on sections spanning the estuary in front of the town's historic castle was worse than anticipated and work is continuing.
Councillor Dave Cowans, cabinet member for highways, said: "I decided that, on balance, it would be more efficient and cost effective to carry out these additional works whilst the scaffolding is on site, rather than arrange more work in a couple of years."
He said that as it was the largest bridge the council is responsible for, it was essential it is "sound for many years to come".
The refurbishment work was described as "complicated" by engineers overseeing the scheme and has involved constructing scaffolding under arches above the river estuary.
Workers have also had to deal with pigeons. They said at the start of the project they expected to recover a skip full of droppings during maintenance.
Work to refurbish a major road bridge in the town of Conwy will be extended, it has been decided.