Wendy Martin fired the ladies into the lead 10 minutes into the second half and Katie O'Leary then struck the woodwork.
However, Lewes were always in the game, struck the crossbar themselves and found an equaliser on 68 minutes through Kirstie Spice.
That's how it stayed - and the ladies remain unbeaten in the FAWPL in 2015.
"A few of the players weren't at the top of their games and collectively, it wasn't the best performance, so to come away with a draw is a positive," said manager, Karen Hills.
"We struggled to create chances on this occasion and it's always a difficult game at Lewes so we'll take the point and move on.
"Thursday night will be completely different, a cup final and we're all looking forward to it. Lewes was tough for us so we'll draw a line under that one and now move on to preparing for Charlton on Thursday night."
Spurs Ladies' first cup final in three years is against Charlton at Ware FC this Thursday, April 16, kick-off 7.30pm - come and show your support!
Spurs Ladies vs Lewes: Toni-Anne Wayne; Sophie McLean, Jenna Schillaci, Leah Rawle, Lucia Leon; Maya Vio, Wendy Martin, Riana Soobadoo (Shannon Maloney, 70); Rosie Kmita (Bianca Baptiste, 60), Katie O'Leary, Avilla Bergin.