If your number of chips left drops below 1000 (you must leave all tables and visit your Profile page to see the current status), you have an option to get some extra chips which should allow you to play poker even if you lost all chips before. The Get more chips button is located at your Profile page and, of course, there are some restrictions of its usage:
You can use this feature only once in 24 hours and the countdown is started after the last chips rebuy. The Profile page will inform you when you can get more chips again.
The number of chips depends on your membership level. Non-paying members (Brain Pawn level) can get 250 chips and paying members will be given 500 chips.
This system ensures that nobody can get too many free chips for nothing, so if you want to get to a high-stakes table, you must really win at many normal ones in order to accumulate the required buy-in amount. However, if you lose everything, you can still try your luck again in 24 hours.