Only by keep resyncing/rebooting until it changes (but not too often). EE public IPs are fairly sticky. What type of BB do you have?
1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 20 Meg WBC => 2020: EE 40 Meg FTTC (no landline no.)