GPT business is a lucrative one but you need a lot of members to be able to make some bucks, i will suggest few ways to earn more money from your GPT website since you do not mention your current method/s of monetizing it.
1, Offerwall
2, Games
3, Monetize your shorten link
4, PPD methods.
I have 1 & 2.
Point me in the right direction for 3 & 4 if you could.
I have quite a bit of traffic as well