"And if so how can I do it"
Please note that DomPens are considered disposable vaporizers. This means, once you have finished the oil in the chamber, you can discard or recycle the pen. Unfortunately there is not currently a way to refill DomPens.
Below I've included an article with more information on disposable vaporizers - Everything You Need to Know About Disposable Vape Pens.
I hope this information helps! :-)