Bankroll for full time play

[baztalkspoker]

I've been a semi-pro now for over a year and was a serious amateur for years before that. Now I've come to a point where I will be full-time pro. My bankroll discipline is something I've been working on a lot lately. I've been working off a 1% risk of ruin requirement to move up stakes. This I think was fine for when I didn't 100% rely on my poker winnings. But when factoring in that I now will be relying on poker for virtually all of my income and so I will be looking to remove $4k a month from my bankroll I think it's no longer strict enough.
Is there any Risk of ruin formulas formulas available which could factor in withdrawals from yoiur bankroll?