multiple diplomacy checks

[Gwaedh]

Diplomacy
If you succeed, the character's attitude toward you is improved by one step. For every 5 by which your check result exceeds the DC, the character's attitude toward you increases by one additional step. A creature's attitude cannot be shifted more than two steps up in this way, although the GM can override this rule in some situations.

Are characters allowed to make multiple diplomacy checks to gradually improve an NPCs attitude in stages? By the rules you can increase the attitude by multiple steps if you exceed the initial DC by 5. But are their any limitations on repeated attempts?

[Are]

No, that wouldn't normally be possible. The two quotes below say that attitude shifts normally last up to 4 hours, and that you can't use Diplomacy to influence attitude more than once per 24 hours. Together, that means it's only by GM discretion that you'd be able to gradually improve someone's attitude by way of Diplomacy.

PRD wrote:

You cannot use Diplomacy against a creature that does not understand you or has an Intelligence of 3 or less. Diplomacy is generally ineffective in combat and against creatures that intend to harm you or your allies in the immediate future. Any attitude shift caused through Diplomacy generally lasts for 1d4 hours but can last much longer or shorter depending upon the situation (GM discretion).

PRD wrote:

Try Again: You cannot use Diplomacy to influence a given creature's attitude more than once in a 24-hour period. If a request is refused, the result does not change with additional checks, although other requests might be made. You can retry Diplomacy checks made to gather information.

[Redneckdevil]

I dont think so. I know u can only go up 2 steps by beating the dc and the effects lasts 1d4 hours. Though i do think the rule does give GMs the power to bypass that for certain situations.