2-Step Mediation With Multi-level Data

I have data in which each participant responded 5 times to some questions. We want to run a mediation model in with X --> M1 --> M2 --> Y, but we want to account for the fact that M1, M2 and Y are nested within participants. Can anyone help?
Thanks in advance!
you probably want to use a latent growth curve model.

That should account for the repeated measure, though there are a number of approaches you can take, an autoregressive model can work as well.

Finally there is the tried and true hierarchical linear modeling approach.