Yes you can, this is known as releasing equity subject to affordability checks by your lender.
Say you have a mortgage worth £400,000 on a property that is worth £500,000. The £100,000 difference between what you’ve borrowed and the value is the equity.
Now if, in this same situation, over the course of a few years, your property goes up in value, say by another £100,000. Then the equity in your property has increased and, if you so desire, you could choose to remortgage and release some of that equity as cash, while maintaining the same LTV on your loan.
If you do decide to remortgage though, watch out for early repayment charges that your current lender might charge. The chances are, if your increase in equity is large enough, that it will still be worth remortgaging, but you don’t want to be caught off guard by early repayment charges.