Introduce the following:

Level 50 PVP Frontlines Daily Roulette 50 Lore & 20 Scripture
Level 60 PVP Frontlines Daily Roulette 50 Lore & 20 Scripture

Simple. Or they could get more complex but reduce the bonus awarded:

Level 50 PVP Frontlines Secure Daily Bonus 25 Lore & 10 Scripture
Level 50 PVP Frontlines Slaughter Daily Bonus 25 Lore & 10 Scripture
Level 60 PVP Frontlines Seize Daily Bonus 25 Lore & 10 Scripture
Level 60 PVP Frontlines Shatter Daily Bonus 25 Lore & 10 Scripture


Keeping the PVP experience bonuses the same would speed up levelling so that, come 4.0, more players will be lvl50 in PVP.