What kind of hardy hibiscus do you have? I thought H. moschetus (sp?) came back from the roots. The only one I know that comes back along the branches is Rose of Sharon.
Either way, I would imagine you're still safe pruning, to take away the dead parts or for shaping. Hibiscus bloom on new growth.
Others may have more to add.
Barb

All 4 were bought at the same place and same time, but, the only tag I can locate at this time says Blue Bird Rose of Sharon Hibiscus syriacus. I think I'll get the pruners out, as they could use a little shaping, and, of course I want blooms. I appreciate your answering.
Happy Gardening,
Annie