Hi LaBelleDamesansPatience:
BBC Learning pages have great resources (worksheets/ video games) differentiated by age here:
for Early Years/ Foundation Stage (Class R): www.bbc.co.uk/cbeebies/numtums/
For KS1 (Y1/ Y2) here: www.bbc.co.uk/schools/teachers/keystage_1/topics/maths_ks1.shtml
I'm not completely clear where your DD is at: but Starship tv programmes (including web game links & worksheets) go through building blocks of counting to first forays into addtion/ subtraction here: www.bbc.co.uk/schools/starship/parents/mathsresources_tv.shtml
You'll have to do a bit of advanced research to work out which games/ worksheets are appropriate at this point for your DD - but it is a really useful resource.
If issue is counting to 100 - play snakes and ladders.
If the issue is counting back from 100 - play snakes and ladders backwards.
(You can also play multiples - so agree which multiple (say 2s) and then with the roll of the dice (say 5) you know you can move 5 twos - and just count them off (you hold up a finger for each two counted)
If the issue isn't counting but is moving on to addition/ subtraction (say to 20) I'd highly recommend card games.
Addition/ subtraction to 10:
Pick out the Jack/ Queen/ King cards from the deck so you only have Ace to 9. Tell DD Ace is one. Shuffle cards and start playing - each player picks two cards and then works out the sum.
If it will help - this can be done with raisins, m&ms, buttons, etc... so you can make the appropriate piles and then count up -so that she can visualise what the numbers represent whilst she's learning.
If she can't add beyond say 3 - then just start with cards up to 3 and gradually add more in to make it challenging.
Addition to 20: Same game but include Jack and say it is 10. - but this time just pick one card (say 9) and then work out what you would have to add to 9 to make 20.
Addition to 30 - Same game but include Queen and say it is 20. (can play this either with one or two cards). If still using raisins/ smarties (buy in lots).
HTH