There's no way to increase attributes of a ruler. Monarchies have to wait for heir to take the throne, and cross their fingers for the next. Republics get a new chance every four years because of elections (Okay, not Republican Dictatorships, they have the same guy til he dies).
Personal unions require good relations and high prestige to remain in place when a monarch dies. You can find out a lot of great information when you hover the mouse over a monarch's name. It says essentially what will happen when they die: Personal union continues, ends, inheritance, new heir, new heir and pretenders, etc. It's not always perfectly accurate but gives you a hint.
Iirc the mouse over is accurate, for that exact time, it can however change and very often does.
I am playing the mameluks in DW, how do I get to reform the goverment? There is an option to westernize, but not one to reform the Govt.
What level is your gov tech?
In HTTT, the requirements and effects for enacting this decision are different per type of tribal government. However, most of the requirements are common to all three:
1. Nation must be a Tribal Federation, Tribal Democracy or Tribal Despotism
2. Ruler must have administrative skill of 7 or higher
3. At least one of the Centralization/Decentralization or Innovation/Narrowminded sliders is at 2 or higher.
4. The country or a neighbouring country must be in the Western, Eastern or Muslim tech group
5. Tech level 10 in Government Tech
6. Stability 2 or higher
7. Be at peace
As a Tribal Federation or Tribal Despotism, an additional requirement is:
1. Legitimacy 70 or higher
In the latest public beta (April 29, 2010) the slider requirements are to have less than +2 on both of Centralization/Decentralization and Innovation/Narrowminded sliders.
It may not show up as an option till you reach that threshold, many other decisions act the same way.