Use an Integrator block and enable its "Reset" inport, which can receive your "reset" or "trigger" signal.
The input to the Integrator block is a Constant value of 1. Once reset or triggered, the Integrator block ouptut value will increase from zero at the same pace as the simulation clock.
Feed this "time/clock" signal to an 1-D Lookup Table block. The table data is your [time, signal] value.
Every time the clock starts from zero and increases, the output of the Lookup Table block will be this restarted signal.
