The site, owned by Party-Gaming, has approached agencies about pitching for the business.
In the past year, it spent £1 million on advertising - mainly on press and outdoor.
PartyPoker is expected to receive a financial boost following the successful flotation of PartyGaming in June, which valued the company at around £5 billion.
Carat handled PartyPoker's launch campaign, but it is unclear whether the agency will repitch for the business.
Launched in 2001, PartyPoker claims to be one of the world's largest online gaming sites with up to 70,000 players online simultaneously. Its main rivals in the UK include World Poker Exchange, 888.com and Paradise Poker.
PartyGaming, which also operates the bingo site PartyBingo.com, reported revenues of $601.6 million in 2004, with 92 per cent coming from online poker.