Adding sugar after fermentation has slowed down.

I have a coopers IPA brewing right now and it has been in the fermentation vessel for about 8 days. It is still active (I hear bubbles every now and then, but minutes pass between them). Now I realised that I want the ABW to be higher. Is it possible to just add 500 gr of table sugar at this stage, and bottle it in about 4 days?

You should really check the gravity 2-3 days in a row to determine if fermentation is finished. If it does not change then you are good to go for bottling.

If you add table/simple sugar you may get a cidery note to the beer. Of course it all depends on the concentration of sugar and all but you can definitely dry out your beer with sugar.

If you add sugar though be sure to wait until the gravity is stable otherwise you could end up with bottle bombs!! That would not be good!

Depending on the temperature of the beer now you may want to warm it up to around 70-72 to maybe "kickstart" your yeast. If the yeasts are cold they tend to be very slow at their job, warming them up may help them finish faster!

Just a thought!