display of political strength that would have been unthinkable under the junta that ruled the country with an iron fist for decades.
The meeting highlighted the myriad challenges facing the opposition, including its lack of experience as well as internal divisions which saw four members banned from attending, accused of trying to influence the voting.
Suu Kyi's National League for Democracy (NLD) had faced calls to inject new blood into its top ranks, dominated by senior members including some in their 80s and 90s, as it eyes key elections due to be held in 2015.
But the party held back from a substantial revamp of its leadership, instead selecting older veteran party members to a core executive of 15 and unanimously reappointing Suu Kyi as chairwoman.
"We have to seize the chance," Suu Kyi, a former political prisoner who entered parliament last year, urged the party as it gears up for what is expected to be a major victory if the 2015 vote is free and fair.
"I thank the members who struggled hand-in-hand with the NLD for 25 years, and I also welcome our new members," she said. "A party can be energetic if it's refreshed with new blood all the time."
After being sidelined by Myanmar's military rulers for two decades, the party entered the political mainstream last year as a result of sweeping reforms initiated by a new reformist government.
Although hugely popular in Myanmar, some experts question whether the NLD is ready to run an impoverished nation whose economy, education and health systems were left in tatters by the corrupt former junta.
"They could not take power over the country tomorrow. They are not ready. They have a lack of capacity," said a Western diplomat who did not want to be named.
Faultlines have also been detected between the older top party officials -- known as the "NLD uncles" -- and a younger generation eager to help steer the party as Myanmar enters a new era.
NLD spokesman Han Tha Myint said the party recognised the need to gradually promote younger activists.
"That's our main concern -- most of our senior leaders are getting old," he said.
"That's why we have decided that the capacity of our youth must be built up and we must recruit some competent people from outside."
The NLD faces the financial and political might of President Thein Sein's Union Solidarity and Development Party (USDP), created by former generals who shed their uniforms to run for office in controversial elections held in 2010.
The congress is the latest sign of the dramatic changes seen in Myanmar since a quasi-civilian regime, led by former general Thein Sein, took power in 2011, ending years of isolation and heralding a flood of aid and investment.
Suu Kyi, 67, has said she is ready to become president if the NLD takes power, but a constitutional rule now bars her from the role as she was married to a Briton and has two sons who are foreign nationals.
The NLD -- which says it now has 1.3 million members across the country -- swept to a landslide election victory in 1990, when Suu Kyi was under house arrest, but the junta never recognised the result.
The party refused to take part in polls in 2010 mainly because of rules that would have forced it to expel imprisoned members.