Question: My problem is every time after changing the Liferay `portal-properties` (and this is frequent especially at beginning of a new portal project) I need to restart the whole portal.

Some properties I can set over hook and these values will be changed after redeployment. Also that must be possible to change most portal properties at run time. 

However, do you know some approach to reflect changes in `portal-ext.properties` without restarting Liferay portal?

Answer: 
I know it is a very old thread but it may be helpful for someone who is looking for some type of work around  

As we know there is no straight forward way for this but I did this by using java reflection and class loader.

Liferay Version : 6.x

```
//Loading the PropsUtil class by using PortalClassLoader
Class<?> prospsUtilClass = PortalClassLoaderUtil.getClassLoader().loadClass("com.liferay.portal.util.PropsUtil");
//getting the reload method of PropsUtil class
Method reloadMethod = prospsUtilClass.getMethod("reload", null);
//Invoking the static reload method 
reloadMethod.invoke(null, null);

```

Reload method (re)loads the portal-ext properties to the portal so we can use new properties without restarting Liferay server.
This has also been asked in Liferay forums:

<https://www.liferay.com/community/forums/-/message_boards/message/800954>

But I am afraid that most properties are only read once during portal startup.
Usually, the use of a properties file as in this case has this drawback.

There's even an issue open at Liferay about this, but is still unresolved:

<http://issues.liferay.com/browse/LEP-5579>