Reset time stamp on data loaded from .mat file in Simulink

I'm trying to load a vector of data from a .mat file into a Simulink program. After being read into the Simulink program, the data stream should be processed through at the same sampling frequency as the Simulink program. Right now, I'm just loading the .mat file into the workspace and using the "From Workspace" block to get it into the Simulink program. This works fine, but I'd like to be able to actuate a trigger to reset the vector and go back to the beginning. This would allow me to cycle through the same data set more than once. What's the easiest way to do this? I've already tried to paste the vector into an embedded Matlab function, but the vector is too long, so the program just crashes. I've also tried loading the vector using a "From File" block. It also works, but I don't know how to reset it back to the beginning using a trigger. Any ideas?