An application will be submitted to add an extra 250 spaces to the site at Newbridge while an extension of the Lansdown site is ongoing.
The move follows the Liberal Democrat administration's decision to slim down its Bath Transportation Package to reduce costs.
It is part of plans to create 870 new spaces across three park-and-rides.
Last year Bath and North East Somerset Council opted to scrap a rapid transit bus route through the city and shelve plans for a park-and-ride at Bathampton Meadows.
The revised Â£27m package of improvements also includes a reduction to the number of spaces at the Newbridge site, plans to revamp bus stops, work on ten showcase bus routes and improvements to traffic signalling.
The authority had planned to start the project using existing planning approval but has now decided to submit a new application to avoid further delays to the scheme.
Local people will be asked for their views once the plans have been submitted but it is hoped work will start in the autumn.
The cabinet member for transport, Roger Symonds, said: "Nearly 50,000 cars enter Bath every single weekday. The government predicts that this will increase by 15% over the next 10 years - equivalent to an extra 7,500 cars per day.
"Because we will capture more cars travelling to the city from outside, this should reduce the pressure on the city centre network, improve air quality, and make the road environment safer for people on bicycles and on foot."
The improvements also include changes to the A4 junction with Morrison's store and on the A36 at the Windsor Bridge junction.
Politicians in Bath are to launch their latest bid for expansion of one of the city's park-and-ride sites.