If you want higher than five, you could could give your monk permanent Improved Haste (give the monk an "Instant, Permanent" "Haste 2" effect). If you already gave your monk 5 attacks per round, this will get them to 10 attacks per round, the absolute maximum in the game.
The engine continuously recalculates a monk's APR using the UNARMED_DIVISOR value in CLSWPBON.2DA. Setting the base APR, as the others suggest, doesn't work because of this. You need to add an effect to the character to get the engine to do what you want - here's how you do it in EEKeeper:
1. Go to the Effects tab 2. Click Add 3. Type = Stat: Attacks Per Round Modifier [1] 4. Target = Preset Target 5. Flags = Instant, Permanent 6. Key Modifier = 1 (Adds 1 to your base APR of 4 to make it the max of 5) 7. Click OK
If you want to go higher than that, you will need to do as OlvynChuru says and add a Haste 2 effect. Good luck!
Comments
1. Go to the Effects tab
2. Click Add
3. Type = Stat: Attacks Per Round Modifier [1]
4. Target = Preset Target
5. Flags = Instant, Permanent
6. Key Modifier = 1 (Adds 1 to your base APR of 4 to make it the max of 5)
7. Click OK
If you want to go higher than that, you will need to do as OlvynChuru says and add a Haste 2 effect. Good luck!