The next level is under construction.
If you're stuck on a section I haven't finished yet, I encourage you to visit the Lara Croft Online forums. I will be checking in regularly to answer questions and share info. You're also welcome to contact me directly, but it may take longer to receive a reply. For bug fixes and other tech support, please visit the Square Enix Forums or the Square Enix Support Center.
If you're missing a few collectibles, I have posted these VERY ROUGH level maps with everything revealed:
Hidden City Part 2 - The Upper Paititi walkthrough is not finished yet, but you can see the collectibles on this Hidden City Rough Map.
City of the Serpent (no collectibles)
Thanks for your patience and happy raiding! :D