Singapore Airlines runs two separate loyalty programs; KrisFlyer where all Star Alliance airline flights apply and PPS/Solitaire where only Singapore Airlines flight ($$$$$) apply.
Singapore Airlines KrisFlyer program is based on the miles flow and PPS/Solitaire is entirely based on the money spend. Now the airline is introducing some rewards for the PPS/Solitaire while raising the Solitaire qualification criteria.
You can access the Singapore Airlines web page for the changes here.
Here are the PPS & Solitaire Rewards:
PPS Solitaire Requalification Requirement:
You certainly need to spend some serious cash to get benefits out of $ingapore Airline$. I have credited my Star Alliance flights to KrisFlyer over the past couple of years and have Star Alliance Gold status with them (in addition to the lifetime one with United).
Quite frankly, considering the price of the premium tickets charged by the number of airlines, I haven’t purchased premium tickets on Singapore Airlines as of late.