1. Open C:\Program Files (x86)\Steam\steamapps\common\dota 2 beta\dota\bin\client.dll with notepad++
2. Ctrl + F 1134
3. Replace to what ever value you want (1800 is pretty good imo but you may want it lower/higher)
4. ???
5. Profit!
Do it every time Dota 2 updates, or write a script that does it for you.