HALT state is very different to SLEEP state.
To wakeup the processor from DEEP SLEEP, you need to do one of three, depening on your situation.
If you had the processor go in to DEEP SLEEP by a software call (API), you can pulse either RST or CE low, the processor will reset and start. As long as RST is low, it will remain in HALT, as long as CE is high, it will remain in SLEEP.
If you had the processor go into DEEP SLEEP by pulling CE high (or release it, if it's pulled up), then simply re-assert it (pull it to GND) and keep it asserted.