In order to advance through the Tiers of the TopTier Challenge Plus, you need to reach a certain virtual profit target and trade a minimum of 4 sim days on the respective Tier.
Below are the virtual profit targets for each Tier:
Tier 1 - 8% (Unlimited Trading Days)
Tier 2 - 5% (Unlimited Trading Days)
Once you have reached TopTier Trader you do not need to meet any virtual profit targets or minimum sim trading days.