Yes, you sure can change your PV allocation every cut-off. So before your next cut-off starts, you may call the hotline via 211 using your globe mobile (toll free) or you may visit any globe customer service at any globe store, at least 5-10 days before your next cut-off starts so that on the day your cut-off starts, you may then receive a confirmation message that your request has been processed.
Thanks and best regards!
You may change your plan every cut-off via MyAccount at http://accounts.globe.com.ph
Read Self-Service to learn more. For further assistance, I suggest you to raise this to our Twitter Specialists at http://www.twitter.com/talk2GLOBE or any of our support channels listed at http://www.globe.com.ph/contactus and they'll be more than happy to assist you with your account-specific concern.