When you are running Automatic Reprice the software will upload to Amazon in the following conditions:
• if 25 minutes have passed from the last upload,
• or if it finished repricing a batch of 1000 items,
• or if it's gone through a complete cycle (all items in inventory repriced).
Also, it will not upload if another batch is still waiting to be processed by Amazon - after every upload made, Seller Engine Plus waits for the processing report to be delivered by Amazon and only after that point will it upload another batch.
You can check Automatic Reprice by viewing the log for this process, just click the View Log button right next to the Automatic Reprice one in the Pricer Toolbar, see screen shot below.