The new plans were announced by UDD chair Tida Tawornseth at the "war drum" meeting held at the Liptapanlop Hall in the Chalerm Phra Kiat Sports Stadium in Muang district of Nakhon Ratchasima province on Sunday.
The meeting was attended by about 4,000 leading UDD members from around the country.
"Unlike the last meeting when we focused on fighting against a military coup, we now see the situation has changed. The ammart, or aristocratic elite, are trampling on democracy-loving people. We have to revise our strategies," Mrs Tida said in her opening speech.
She said the UDD previously adhered to a two-prong strategy of working within the House of Representatives and outside of it.
"Since the House of Representatives is temporarily not functioning, we have to review our strategy. We will have to fight with two main 'legs'. The red shirts will form one leg and democracy-loving people the other," Mrs Tida said.
The UDD chair announced that the UDD's four main targets will be the PDRC led by Suthep Thaugsuban, the "fraudulent independent agencies of the aristocratic elite", the judicial system, which is marred by injustice, and the use of the armed forces for a coup.
She called on UDD leaders to unite and exchange opinions and provide suggestions on ways of advancing the struggle.
"We will continue to fight so that our long struggle will not be in vain. We have been fighting for eight years in a democratic movement. Today, we can't afford to yield to hooliganism. We have to try to win the hearts of the non-red shirts. We have to fight with rationale because we don't want to suffer any more losses. We will fight until victory," Mrs Tida said.
Red shirt leader Jatuporn Prompan said the fight to come would be much more difficult than the previous ones. It was necessary for all red shirts to think of how to get rid of Mr Suthep and those who were standing behind him.
"If we, the red shirts, do not come out, this government and democratic rule will be completely brought down by March," he said.
Mr Jatuporn said the problem facing the UDD was not only Mr Suthep, but also the network of ammart or aristocratic elites - the same group of people behind the Sept 19, 2006 coup and the 2010 political violence.
"From today we will have to fight until victory. We have two choices - to win or get killed. We have to teach Suthep a lesson for challenging the UDD," he said.