People who are hearing-impaired must wear earpieces in their ear(s) most of the day, most every day.
First, it is important to keep both these plugs and your ear canals clean and clear to avoid the risk of an auditory canal infection.
Audiologists recommend using an alcohol-free, broad-spectrum anti-microbial cleanser for hearing aids, daily. It's for external use only. You also don't know how the plastic will react with other cleansers containing alcohol. Pharmacies will also have these kinds of supplies. Several different products are available, any of which will be suitable. They are sold in small pump-spray atomizer-topped bottles.
There's no reason that you can't treat your ear plugs similarly:
A light spray on a clean tissue which you then use to wipe-down the surface of your plugs.
Do this when you remove them so they're dry and ready for re-use.
One of the reasons for the popularity of the disposable ear plugs is the convenience of tossing and replacing a pair rather than the time and additional expense of proper maintenance. Also, if you are willing to care for your disposable ones, it might be to your advantage to get a better quality, higher performance pair for your prolonged use.
The cheap dispo- ones are more for occasional temporary use.