Hopefully, you will not lose the count so badly that you cannot come to a workable approximation. This should allow you to make the appropriate wager on the next hand.
The money is made primarily due to bet variation, not strategy variation. If you don't feel confident approximating when you have dropped the exact count, you need to put in some more time at the kitchen table.
Do not fall into the strategy variation game. While strategy variation will increase your winning rate, it is a very distant second to the increase realized by getting the money out there when the count is up. Be wary of those who urge that you memorize a hundred or so variations. Be particularly suspicious of authors who insist that it is necessary to learn one strategy for 1dk, vary it for 2dk and then again for shoes. They are filling books with index tables.
If such things come easy to you, then great, enjoy the mental exercise. But if you are like most, when you are new you will simply tire yourself trying to gain that extra .2% because you have been persuaded that you have to utilize the sexiest, nuclear powered indexes in existence. Then, because your brain is on overload, you will drop the count and fail to realize that you should have a max bet out there.
Perhaps you have been playing too long w/o a break.
If you've been playing for more than an hour or drinking, then this is a good time for a break. If the count is very high, then continue playing for the rest of the shoe with, as you suggested, a lower estimate of the count so you are not betting to much for your EV.
Suppose you lose the count in a 6D game with 3 decks left unplayed and the last reliable count you had was an RC of +9, which translate to a (single level count) TC of +3.
Now a question: if the game was set up so that the 6 decks had 9 extra high cards added and 9 low cards removed and you were not allowed to play unless blindfolded with your only knowledge of the cards dealt is the dealer telling you your score and his/her upcard for each hand, would you still play?
Think about it.
In the first situation, would it not make sense to play the rest of the shoe (i.e., the ~1� decks left 'til the cut card) as though the TC was always +3?
I'd be interesting in hearing others' opinions, thoughts, on this.