snakes and ladders - what happens when you go up a ladder or down a snake?

Hello.

My question is not about the random number generator for dice in board games but about my piece position and my score.

When the dice goes to a random number, that number is added to the current total and moves to the relevant spot on the board game (see variables). Thus, if they currently have 3 and the dice roll gives them 6, their total is now 9.

However, if they land on, say, 17 (because their total is 17) they will slide back to 9 (see the gameboard attachment).  Their total is still 17 but they are at 9.  If they get another 6, they go to 23 instead of 15.

The question is: how do I resolve the conflict between the increasing total and the fact that the user might go back down the board?

Thanks for your help.

Iffaf