Waveshaper: Amplitude changing as frequency changes
I am not quite sure that I can fully understand what you are intending to achieve with your circuit configuration but there are a couple of problems that you need to correct.


Get rid of the capacitor C1. The reason you are getting clipping is because you are asking the second opamp to produce an output that is 10V peak and yet the power supply to that opamp is only 9V. Increase the power supply to a higher value like 12V.
I believe that you need to be setting up your input saw tooth waveform to be a bipolar signal instead of one that goes from 0 to 5V. (But I may be misunderstanding your design intent so maybe you could describe in your question a bit more how you wanted this circuit to function).